Yeah, I can appreciate why Google would only hide the clues in the Chrome Google Books app, but I'm a little disappointed in Rovio. I have bought their apps on 4 platforms already (Android, iOS, webOS, and Android). I'm not interested in getting another one.
BTW, this is actually the second time that Google arranged an exclusive. Back in July OK Go released a new music video that could only be viewed via Chrome. I remarked at the time that this was a waste because it ignored 85% of the browser market.
The same applies here, only it's probably even more true for Rovio. What do you want to bet that iOS+Android is actually 90% of their market, not 85%? Given that Angry Birds works best on a tablet or the iPad, I think so.