I spent a bunch of time reading reviews of various iPhone FM transmitters before buying this one. I've used it now for several weeks, so it seems only fair for me to pass on my views since I relied on these user reviews so much in selecting the product in the first place.
(1) The sound quality does seem better than other FM transmitters I've tried. I let it find a frequency and tuned the radio to it, and haven't had any interference, ghosting etc. I live in Washington DC and have found other FM transmitters just have too much interference to work effectively. So far, this gets full marks on sound quality, which is probably the most important issue to think about when buying one of these things. (If you haven't used FM transmitters before - understand one thing: the FCC limits the power output of these little transmitters to the point that they can be easily overwhelmed by interference, static, distant real radio stations, etc. - so finding one that actually works and puts out a strong enough signal to work effectively is really not easy. This one does manage it.)
(2) The mount does hold the phone securely and it is relatively easy to take the phone in and out of.
(3) The little dongle cord to plug the phone in is kind of klutzy. Basically, you have to plug the base of the phone into the dongle, then squeeze the arms that hold the phone together, every time you put the phone in the mount. It would be better to just drop the phone into the mount with a pre-set plug, then squeeze the arms together, but this is a fairly trivial issue. The other annoying thing about the dongle is that because it is loose, if you don't drop the phone in and connect it, it swings freely and knocks against other parts of the transmitter as you drive. You are basically compelled to hook up your phone every time.
(4) The plug going into the cigarette lighter holds the whole thing VERY securely. In fact, it holds so securely that I can't even get it out of the lighter plug. I think I would have to force it to pull it out, and I fear I'd break the whole thing if I pulled on it that hard. So, whether you intend it or not, this may be a permanent mount for you.
(5) I like how the screen can pivot on the phone and still hold securely. Depending on your car layout, this means you could use the mount for passengers to watch videos on the iPhone screen.
(6) The gooseneck seems sturdy enough. I am sure it will break eventually with hard use, but it should hold up for a reasonable period of time.
(7) If I had more problems finding a working station, it would annoy me that the frequency read-out on the thing is on the top of the mount instead of somewhere on the front, where I could easily read it. Since I haven't had any issues with the station it selected for me initially, I can't really ding the thing seriously for that.
Note: my car does have blue-tooth for the phone, so I haven't even tried the speakerphone thing. The only thing I can say about that is that it requires you to plug a little cable into the headphone jack AND plug in the dongle to make that work, which is a pretty inelegant solution. I'd think you'd be better off with a bluetooth headset vs this rather klutzy set-up, but look to other reviews if this is important to you.
Bottom Line: If your car doesn't have a tape deck and you don't want to spend $100s paying somebody to take your dashboard apart to give you an auxiliary input port in your car, this is a reasonable choice. It's not a perfect product, but it gets the job done. I don't regret buying it, even though it seems to be permanently stuck in my cigarette lighter. That is a measure of how much better it actually works than several of the other FM transmitters I've bought over the years.