Well its obvious use for the android OS is something. Do developers here have any success with games on the google store or is it pretty hit and miss?
It is hit-and-miss, but not because of the nature of the store.
Too many people develop games and hope to sell them with no business sense. They have a "build it and they will come" mentality.
When it comes to any revenue it boils down to simple math:
Number of people who visit * visitors who actually buy * buyer's amount they spend = revenue.
You need proper advertising and brand awareness to build the first one.
You need a proper product that is slick and polished and tested for the second one.
You need to charge enough that they can afford but not so much that they balk for the third one.
There are many tricks to fine tune each number --- figure out why people are visiting but then stop short of buying, figuring out exactly how much you can charge, etc., but it still boils down to those three issues.
Too many products just leave the first number at zero, and let the zero multiply right through the other factors.