I currently have the Charge and owned the DX before it. I loved the DX, very reliable phone and well built, and even though the bootloader was locked there were plenty of options to speed the phone up and make it better overall.
The Charge is nice, the 4G is very fast. But here's the thing... it's only good if the phone can hold 4G or if you're in a 4G area. I live in Fairfax, VA, and while I can get 4G signal, it's very "finicky" to say the least. Not only that, but 4G will drop out at times and the handoff to 3G takes a minute or two, but sometimes it will go to 1X for a while then back to either 3G or 4G. I never had signal issues with my DX, held a great 3G signal and the only time it dropped out is when I'm in an area with no Verizon coverage.
The Charge feels cheaply built and while the SAMOLED+ screen is nice, the colors are too vivid and look fake. You can really notice it when watching a video, whereas the DX had a more "natural" screen. I don't use the front camera at all, maybe once. I'm also disappointed with only 327 MB of actual usable RAM by the OS, and I've hit that mark a couple of times so I don't install or use as many apps as I used to. Call quality is ok, not bad but not superb... the DX was much better and held a better signal as well.
To me... Having 4G is nice but not a necessity especially when Verizon's LTE network is practically brand new. I'm thinking about returning it to Costco since I'm within the 90 day period and getting an X2, something more reliable and quicker. I'm going to wait until next week to see if official word of the Bionic comes out though.
Oh, and I know I compared the Charge to the DX, but most of the features I mentioned are still included and possibly improved on the DX2.