Nope, wouldn't replace it. Coming from the Droid 1 the 4 is nothing but good. Haven't had a problem with battery life overall compared to the D1, though it's not amazingly long lasting or anything. And my favorite part is the keyboard. Once you get accustomed to it (and its small key placement quirks), it's pretty amazing how fast and comfortable it is to type on.
My biggest problem with the D4 is the software. I got rid of the motorola home screen ASAP and rooted and removed as much bloatware as I could, so it's acceptable for the time being, but it would still be great to get a good fresh, clean ROM on there. But really that's not a problem with the phone; it's a problem with Moto/Verizon.