I have never been all that thrilled with the concept of convergence devices because, while its nice to have one device rather than 3 or 4, when you eventually have the battery run out (or you forget it at home) you're left in a position whey you have to live without your Phone, MP3 player and PDA all at the same time. While these devices are all luxuries, it is still very frustrating to be without one after you've become accustomed to having it around.
Being that videogames require the screen to be on and displaying images the entire time, typically are playing music and sounds at all time, and are (about) the most demanding applications on your GPU and CPU they probably will drain the battery faster than anything else you do on your iPhone or iPod touch. Now, I could be wrong but I suspect that if you have to plug in your iPhone/iPod touch every night to charge it because you play games on it people will become frustrated and stop playing games on it.
This may sound odd that battery life would impact how people use their device, but I have noticed it in how I deal with my phone. A couple of years ago I bought a MotoRazr which was one of the nicest form factors for a cell phone I have ever used ... The unfortunate thing is the RAZR has never had a particularly good battery life, and as it has aged it has only gotten worse. The battery life has gotten so bad that I only open the phone once or twice a day to check to see if I have received any messages, or whether the phone has accidently been set to silent.
