Here are my unprofessional opinions and findings:
I wasn't able to view the 60-inch PK550 next to the 54 G25, but I was able to view a 50 inch G25 next to a 50 inch Pk550, so it was a good comparison. Both sets were running the same demo blue-ray DVD (from Panasonic, interestingly enough).I don't know all the techno-jargon, but here is my review:
Blacks (1)
No point dancing around it, the G25 was better. There were three scenes that showed this: 1) Black screen with two yellow flowers in the center 2) A night-time shot of London's "Big Ben" where the only non-black on the screen was the clock face and 3) Some sort of 50's style neon sign on a black background. In this case the G25 came out strong - the blacks were like a void of darkness. No hint of gray or anything. It also beat everything around it, not just the LG. In the flowers picture, it might have been too dark - or maybe the flowers were too vivid, not sure which, looked a little "stuck on", or "not real" but hardly a serious complaint.
The 50PK550 did very well though and was at least as good or better than everything around it - except the G25. I walked over to the 60-inch PK550 (the one I eventually bought) and without the G25 sitting next door, the blacks looked awesome with the same demo DVD running.
I'd characterize the difference as certainly noticeable, but not terrible and more a testament to how good the G25 black level is, not really a negative on the LG. As I said, the LG was as good or better than everything else, only the G25 stood out and killed the whole row.
Blacks (2)
Interestingly, the difference in the black level was only noticeable when the scenes were mostly black with some bright picture in the middle. In scenes where there were blacks and shadows but not over the majority of the screen, I saw little difference. An example was a scene with a bunch of jet skis - all the black seats looked the same to me. Same with a scene with a classic car, shadows and blacks looked equal. My guess is under exact testing they wouldn't be, but to my eye in these cases there was no difference.
Color
Both sets seems very good here. There were differences though and I'm not sure if they are good, bad or up to personal preference. First, a scene with a grassy field and a tree in the middle. It looked really good on both TVs but on the G25 it was like "Oh look, a really nice tree and grass" on the PK550 though it was more "Whoa, lovely lawn and where can I get that tree". The basic difference was the LG's image sort of grabbed you more than the G25. The G25 had a great picture, but less eye-catching and a little more muted. The PK550 colors (especially greens) seemed to have a little more self confidence than those on the G25 and the image was better (to me) as a result. Some could argue the G25 was more "correct" - all I can tell you is the LG picture looked more "fun to watch". At this point I noted that the G25 had an edge with mostly black images, but if its a fairly well color mixed scene, the LG seemed to have an advantage, slight perhaps, but there.
Detail / accuracy
I found this the hardest to compare. In some cases I thought the G25 had the advantage, in others, the LG. In most cases I couldn't really detect much difference. The upside of the demo DVD is that the images are the same and they repeat so you can examine the same thing over and over. The down side is that none of the images were images or movies I'd already seen and so it was hard to tell if the images were better, worse, correct, accurate, etc. About all I can say is that if the images were true to the live image, then both TVs were accurate. If they were woefully inaccurate, then both were equally bad . Sometimes I thought the LG was sharper, others the G25. All in all, I didn't see anything to make me give either TV a definitive edge. I was using human eyes here, not fancy gadgets, so your results may vary
Glare
The G25 walked over and pummeled just about every other TV in the store. It took no prisoners, gave no reprieves and laughed at the very idea of mercy. If you ask me, there is no better anti glare set than the G25, at least out of the 40-odd TV's they had in the store. That said, I think the glare issue on the LGPK550 has been over stated. Does it have more glare than the G25?...um...yes. Does it have more glare than other TV's?......sometimes. Is it as bad as I expected?....no, not at all. The store was well lit and the LG was nearest the main bay windows and entry (not exactly the best place for a TV with some possible glare issues....but I don't run the store). The first thing I did was to turn it off. The screen reflected....well It was a pretty good reflection and in a pinch, could be used as an emergency mirror. Turn it on though, and most of the reflections vanished. I could still make out a reflection from the main entry and the bright brand-name signs behind me. I walked down the row of 20 -odd TV's to compare (Samsungs, Sonys, another brand I forget and a Panasonic Vt25). The LG might have been a bit more reflective, but not by much and I'd say the off-state reflectiveness was the same as my current RP set, telling me that a little light control will go along way with the PK550. Remember too that this was in a bright store with a 40-foot window-wall and door about 30 feet away, at a right angle, to the line of TVs (and a bright sunny day too). The 60 LGPK550 was the first TV in line and so closest to the window wall. Bottom line is it does have glare and it's probably more than some other brands but I didn't find it "horrific" even under these bright conditions. My guess is some typical light control (blinds, curtains, etc) will make all the difference and better still if you mostly watch in the evening. I tested my living room first by blocking as much light as possible using conventional methods (blinds, curtains and a towel over the door window) It was significantly darker than the store and so while I haven't set up the LG in my room yet, I have no worries about glare. Overall I didn't see any huge glare differences except when compared to the G25.
Other stuff that may or may not matter to anyone else:
- Online connectivity: Well the G25 wins here because the LGPK550 doesn't have it. So that's pretty much that. For me, the only thing I want to use that requires online connectivity is Netflix and my current Wii or a Roku will fix that.
- Ability to process 1080p/24PFS without 2:3 pulldown: The LG wins here because the G25 can't do it. This gets a little technical for me being a Noob in TV land but from what I think I know, this means the LG wont flicker as much in certain instances and can handle the frame rate without using 2:3 pulldown (and lets be clear, I'm not exactly sure yet what 2:3 pull down is). What I did learn is that it might not even matter - apparently I've been watching 2:3 pulldown all along and some people can't even tell the difference anyway. If you're interested in this techie stuff - awesome, but don't take my word for any of it - I just report what I think I understand - I might have this wrong - All I can really state is that the LG doesn't have to use 2:3 pulldown for 24FPS - whether that actually matters...who knows
THX Mode: I don't think the PK550 has one, so , one up for the G25. That said though, I'm not really sure why it is you cant just calibrate the PK550 to be THX-like, if that's what you want. The PK550 apparently has one of the most complete calibration suites in the price range (according to Video Only) with multiple "modes" to adjust - why couldn't you just configure one of the modes to be THX-ish? I suppose convenience and pre-calibration come into play with a factory THX mode.
Thinner "frame": The LGPK550 has a very thin frame, and its pretty thin in general. In the space I have, I was limited to a 58-inch set due to the general thickness of the frame that surrounds a 58-inch TV. Thanks to LG's somewhat nicer design with thinner frame, I was able to fit a 60-inch set in the same space. For example, the Panasonic VT25 with a 58-inch screen is 56.3 inches wide, the 58S2 is 56.1 inches wide. The LG PK550 with a 60-inch screen is only 54.8 inches wide. Basically more screen, less frame. If your sticking the TV on a wall, this probably doesn't matter. For me though, I have a maximum width that would fit in the space I have - the LG enabled me to go to a bigger screen saving about 2 inches on the frame thickness.
Lastly, a note about the PK750 and PK950. Apparently the 750 has some unresolved "issues" that effect the picture quality and the 950, while having better glare control, also has a reduction on picture quality thanks to the way LG decided to control the glare. This comes from the folks at Video Only - who after seeing both sets, decided not to carry them. Both these sets have more features like online connectivity, etc, but at a price (other than $$$ that is). I can't state for sure thatteh 750 and 950 were not as good, thsi was just the opinion of the store people (though they seemed knowledgeable )