iphone4s Battery ?s from a soon to be Android convert

Hello. I presently have an Evo 4G android phone and am making the switch to the iphone 4s.. I think...

Are the reports of poor battery life real.. and is this a major issue for current users?  I have read  articles about the battery.. but this still isn't quite clear to me..  I'm not sure if it is just a few people griping on a widespread problem.

After suffering from a laggy android phone (I'lll admit it) I am looking forward to a switch to Apple.  I also considered the Galaxy Nexus.. but am up for something different. I like the camera on the 4s and think ios is snappier

My only other concern is (I think) Apple is a bit sleazy with software updates.  For example, Siri was not given to iphone 4 users.  It seems that GPS could be coming soon.. I'd hate for it to be available on iphone 5 and not prior releases... I guess there is no way to know..  I know that Android development is all over the place with device fragmentation.. but I think with Nexus phones, Google does a good job of making sure the last version can run the new software.....

Thanks!