I've got both phones. I bought the Maxx outright and purchased the G2 after the unlimited data glitch this past weekend.
I like the G2 for the onscreen buttons, improved camera, and the fact that it is noticeably lighter. Battery life has been great. It doesn't last as long as the Maxx but it's close. I do miss the voice activation (I didn't use it much though) and the camera UI on the Maxx.
Biggest win for me was that it looks like developers are starting to take a look at the G2. LG finally put together a well rounded powerhouse of a phone.