Ok.....I know I am late to the game with this but I have the HTC Evo 4G and LOVE IT! I have never had the battery run down on me and I use the dam thing endlessly throughout the day. If you are just smart and turn crap off that you don't use or need at the time then you will never have a battery problem.
I have ZERO complaints about it, minus the fact that I ended up dropping my first one and shattering the screen, but that was because of some idiotic kid hitting me and it went flying 10 feet in the air and landed on the screen. I love the big screen, but I bought it because it had the large screen because I watch videos and stuff on it all the time. I never have issues with Sprints service, I have 3G wherever I got, as opposed to the G or Edge that I might have gotten on T-Mobile. Glodowg is very jealous of this fact because I get 3G at our house and she is lucky to get G!
I would recommend the Evo to anyone that is looking for a good smart phone. The price of the service - 69.99 a month for 450 anytime minutes, free nights and weekends, free MOBILE TO MOBILE no matter what network the other phone is on, Unlimited Data, Unlimited Texting. $10.00 a month for the 4G service(sucks because not available many places, but come on, it is $10.00!) plus Taxes and everything and my bill is a little over $100.00 a month. I did have the HOTSPOT turned on for a while and that adds $30.00 a month but that is not a necessary thing to have!
DO NOT buy it for the 4G because you can't get 4G at most places yet!