I haven't bought any apps other than More Icons widget and it's such a pain to put in the CC number that it's enough to keep me from needlessly spending a couple bucks here and there.
On my way to work today I was looking at the pictures from the stock camera and remembered about the discussion on the Pro Zoom Camera. So since it was a 2 hour ride and I wasn't driving, I thought I'd go through the effort of typing everything in. Holy crap! I didn't have to! It's stored in the phone.... I'm in trouble now.
Anyway got the app installed and have been playing with it. I like the quality improvement, the added zoom, the filters and I haven't even played with the other available features. There is one irritating thing that I noticed (and as I type this, I wonder if the stock app does the same). When I'm zoomed all the way out, the picture resolution is at 2592 x 1936 as I set the camera to do. But when I zoom in, it drops as low as 640 x 480, depending on how much I zoom in. So really it doesn't seem like zoom, but rather cropping the picture and blowing it up. Seems kind of sneaky.
Still like it much more than the stock. Using the volume button to control the zoom is almost worth the two and a half bucks in itself.