For an Android developer, there are a lot of great talks at I/O, and you have the opportunity to meet the complete Android team and ask them questions.
But last year they reduced the event from three days to just two, and the first day starts with a 3 hour sales pitch for the press.
I met some interesting people there. One of them is working with me now, so that trip was definitely worth it. But I like to experience conferences like short educational trips where I learn new things with other people, and I think 5 days with the Python community will be more fun than another Google show.
(It used to be a lot more affordable, but when people started presuming that they'd seed expensive hardware every year, demand went through the roof.)
If you can get your company to pay for it, go. If you can't, but you are heavily reliant on Google APIs (Android, Chrome, AppEngine, Geo, etc.), you should probably still go. If you work with primarily open tech and are just curious about attending (or if you just want random free shit), it probably isn't worth it.
Worst comes worst, you can consider this as visiting some festival like Mardi gras of Google :P
http://thenextweb.com/google/2013/05/15/google-is-giving-a-f...
On the other hand, maybe it is a better idea to just steer clear of experimental Google APIs, services, etc and just use their core product - search and advertisements. Think Google Code...