I have been using the HiveKeepers app for a couple of months and am generally very happy - certainly the best app I've tried (and I've tried a lot).
The reasons I chose it is that you can log what's flowering on the inspection and store photos of each frame and scroll through them in chronological order which I love. There are at least 3 different ways to log an inspection which is perhaps a little bit over complicated, but if you like storing vast amounts of data this app is probably for you.
We got it from the App Store (Australia) as a free trial first so had a month to play. They seem pretty pro-active with the app too, asking for suggestions/ modifications and I think they are setting up a forum for users to chat.
All in all pretty happy so far