After a long wait, GRASS 7.0 beta is out! See here a summary of what is new in this release. Take your time, is is a long list :-).
In fact, GRASS 7.0 has been available for some time now for those willing to compile it themselves. So have I, and out of experience I can tell you, this is a great release, with tons of new features and improvements, including great speed improvements in handling vector layers, a whole new module for time series analysis, numerous interface improvements, etc.
Really, you should go over to the download page and give it a try! Good change you won’t look back after that.