Nice game, no negative comments except that it is letterbox which I don't like, otherwise, it's very nice, well done.
However, I think you have to put Innes suggestion into your consideration regarding the 30 seconds game play with separate score or something.. it would be nice.
Last point, so what if the players clicked accidentally on the full screen ads? even if it is a bit annoying for some players, but it lets you earn more, full screen ads are a bit annoying anyways, so where is the problem?
I used the full screen ads in my game after the same way right after the bird hits and the game is over, so I'm pretty sure that many players accidentally click on the ads.. but guess what? I was earning $70 to $90 per day from admob full screen ads before the game was removed from the store, so where is the problem?