R3 Beta became open to everyone last night. Still only two game modes are available, Team Deathmatch and Chain Reaction.
The killstreak oriented gameplay might not be for everyone. It can be fun but also it may get old very fast.
Smaller maps and smaller number of players encourages more of strategical holding (aka camping).
The Auger (obtained after 6-kill streak) is way too powerful.
Still this was beta. The game will be released September 6.