I own one of the earlier Pentax waterproof cameras (Optio W10) and it still works.
We decided to upgrade to the WG-2 GPS before our trip to Costa Rica. Prior to buying ours, my company purchased two of the WG-1 GPS cameras and I was able to use them a couple times in the field. I found that it took a really long time for the GPS to locate and was a little disappointed. Once we got the WG-2 GPS I was kind of shocked to see how fast the GPS would locate both in the US and in Costa Rica vs. my experience with the WG-1 GPS. I did not have a stop watch out but I can't remember waiting more than 15 seconds for the GPS to acquire.
We purchased the car charger that came with two extra batteries for around $20. One day we heavily used the Camera and took six 2 minute long videos and ended up going through two batteries. We took probably 20 pictures before our trip, over 1200 on our trip, and about 10 short videos. On our trip we used it snorkeling, ocean fishing, hiking, in the resort pools, zip lines, and whitewater rafting. Having the GPS for the whitewater rafting was pretty cool, using Picasa it placed all our photos on a Google map with little red location pins.
The underwater photos seems significantly better than any we shot with the old W10 but it might have just been clearer water or having more megapixels in this one vs. the 6 mp in the W10. The WG-2 also has the anti shake so that might have been why the pictures are better as well.
We found that the strap for the carabineer liked to slowly loosen I would recommend taking something like a small safety pin and pinning the excess strap to the main strap so it won't slide out. Ours never slid out but I had to shorten it multiple times on our vacation.
One thing I wish they would have designed differently is the metal loop that the camera strap attaches too; it is only wide enough for the strap. On the W10 I would use one of those yellow boat key floatation devices to keep it from sinking to the bottom. Those yellow floaties come on a little metal chain, the ones with the balls/links that snap together. Unfortunately the space for the camera strap is just a little too small for the balls to fit though. I had to strap it though the carabineer strap and if that would slide out while wet then my camera would be at the bottom and the floatie would have only saved the carabineer strap. I ended up using a key chain loop to temporarily attach it as a back up when we went whitewater rafting, the rest of the time it was just hooked through the carabineer loop. I know they make a floatation device for it as part of those bundle kits, out company purchased that and I think the floatation device is too large and cumbersome. One little yellow boat key floatie keep this camera floating in both fresh and salt water.
I found the carabineer very useful on the zip lines and whitewater rafting. Other people had waterproof camera but had them stored away, they were only able to take them out when there were breaks. On the zip line I attached it to the harness loops and during the whitewater rafting I hooked it to the life jacket. I easily took twice as many photos and wasn't holding anyone up waiting for me to put it away.
We used our Joby tripod and set up the camera to take a photo every 5 minutes while we were near the beach. We were there long enough to see high tide and low tide. When it is in this mode the camera appears to be off and then you will see a quick image for a couple seconds just after it took another photo. I was cool to see how much the tide changed especially since large rocks appeared at low tide.
The Macro mode was cool for taking really close shots of flowers and bugs.
Another feature that was new to me from the original W10 camera was they added a nighttime mode that can be used while holding the camera. The old camera only had night time and the shutter was open for so long that any movement caused really blurry pictures. It still has this mode but they added one that allows you to hold the camera and still take great images in the evening.
I am not sure how helpful this rambling review is, but if you are deciding between the WG-1 GPS and WG-2 GPS I would suggest paying extra for the WG-2 if you want GPS. If you don't want GPS then save your money and get the WG-1 without GPS.