The problem with it is that the battery life is unstable, i.e., highly variable from day to day. When everything is working well, I can get 15+ hours of light use running on 4G on the stock battery, and somewhat more than that on wi-fi. However, there are bad days when unidentified rogue processes attack the battery like crazy, and it becomes more like 6 hours if left unattended.
If battery life is important, and you are not near a charger, then some solution such as an extended battery or external battery is going to be necessary.
I like the phone a lot, and between the Thunderbolt and Charge it is largely a matter of personal preference, but I think the general feeling is that the Charge's battery lasts somewhat longer on average but may not be an all day phone, either, with the stock battery. I don't know about the variability of battery life, though, for the Charge.