So I've been following VU for some time (around 2 years now), and it's had a few closed betas, however it's recently been made open to the public and anyone who wants to give it a shot. If you're not sure what it is (which is probably the case for many of you) here is a quote directly from the website:
This doesn't even cover half of the things that are already done to the base game prior to introducing user-generated content. A few things I've noticed right off the bat are
Ugly blue tint that's everywhere on BF3 is finally gone.
You can finally reject revives (no more res trading).
There are now 60hz and 120hz servers whereas the stock game only offers the default 30hz.
Server admins are given full control over what rank, weapons, loadouts, etc. are made available to players
Your account can have multiple soldiers (Only one as of now, but this is to change very Soon™)
You can chat during match endings and during stage transition (wasn't introduced until BF4)
Specular lighting is no longer irritating and invasive. Can also be toggled on and off.
Once you've linked your Origin account and started the game once YOU DON'T NEED ORIGIN. (DRM-FREE BF3 )
Videos
My thoughts: I think this is good for both players and EA itself. You need an actual legit copy of BF3 to play VU so there will no doubt be people ready buy a cheap copy just to play BF3 with mods. From what I've seen these guys are also trying to get VU to be an ESL thing and it's going quite well with a small tourney being held on the 31st of Jan. It's also pretty funny how the Senior VP of EA was once asked about mod tools for BF3 and stated it would be "impossible considering all the environmental changes that take place and how complex the Frostbite engine is." Look who's wrong.