Android App Development has come a LONG way since the operating system was created. Android Apps can do just about anything you want them to and many believe that applications for the Android operating system are better than those for the iPhone (debatable of course!)
Whether you are developing for an android phone or android tablet you will find that the Android Operating System is extremely powerful and easier than many operating systems to program with. You can develop innovative android apps in various fields such as business, entertainment, finance, fitness, games, health, travel, sports, weather, wellness, and many many more. Your level of creativity really is the only limit to what you can create as far as android apps go.
You have to be careful to make sure that your apps will work for previous and current android versions. What you created for Ice Cream Sandwich may not work for Jelly Bean as well as with any forward or backward android versions. This is the same with any operating system that you may have to make tweaks and updates to the program itself to continue to work with the latest OS versions and devices. If you program much at all you probably already know this and have prepared yourself for it.
Not only do you have to develop an application that is functional with a great user interface that looks good and is easy to use, but you must also be unique in your idea and really try to solve a problem that many people have. If you can do this and market the app properly you could see great success. The app should also be fast and smooth with little to no freezing and crashing. You can put it into Google Play and sell directly from a website as well.
Best of Luck!