When I first received my Revo, I was disappointed in battery life, to say the least. It was on par with my Incredible but that sucked, too. In fact, even with my Inc rooted and ROM'd, it sucked in terms of battery. If I took it off of the charger in the AM and made it to 3pm before the 'Connect Your Charger' warning was displayed, I was lucky.
ANYWAY, I was getting an average of 5-6 hours out of the Revo before it needed charging. Granted, my house is in a spotty coverage area but it's never without signal. I'm just lucky to pull a few bars. Regardless, I've been doing quite a bit of searching on the forum, as I'd hate to give away my new Revo so in a last ditch effort, I tried Juice Defender.
If you haven't tried Juice Defender, try it now! Granted, there is a little lag when reestablishing the radios when the screen is unlocked but that is a small price to pay for the increase in battery life. During a full day that included about 90-100 texts, 3 voice calls averaging 20min a piece, some web browsing, Foursquare, and Wikidroid, along with GMail updates, I managed to squeeze about 16.5hrs of life out of the battery before a charger was needed. The Juice Defender widget showed 1.77x and I wholeheartedly believe it. I couldn't ask for better battery life on a 4G phone. My old Droid1, Droid X, and Incredible pale in comparison now!
If you're about to throw the phone, give it a try. I used the Balanced setting and just let the app do its thing.