It's a little ironic that given Android is one of the easier platforms to pirate software, it's also one of the platforms I don't mind paying for software. An app I'll pay for generally meets the following criteria:
- I use it multiple times a day, and will continue to over a long period.
- The developer appears responsive to users regarding features/support.
- It's a reasonable price (in my opinion this is generally less than €1.99).
- It looks good and has an intuitive interface.
The last point is probably the main one and something I think is unfortunately lost on a lot of developers. It's fair to say many programmers aren't good graphic designers. Good is obviously also a subjective term.
Enter the Android UI Guidelines. Google have taken the time to concisely write up guidelines on how an app should look and feel, the benefits of which should be obvious.
Do they stifle creativity or prevent an app from looking distinct? No. But what they will do is help users feel at ease using your app from the get go, and help them run great on as many different devices as possible.
It really frustrates me to see people recommending an app so highly only to download it on my Desire HD to be met with stretched out low res icons, ignoring the use of the dedicated Android hardkeys with ever present settings menus etc.
Apple have a very similar set of guidelines for developing iOS apps, yet they seem to suffer far less from this issue. I don't think the old cliche of fragmentation is at fault here at all, more developers not wishing to follow standards.
Perhaps Google could be a little better at regulating the marketplace also, particularly as the Android tablets start to launch.
Doing it right, the recently redesigned Twitter for Android.