It's a neat little diversion. Pretty good graphics for an iOS game, but it's really just a glorified shooting gallery, not anything like what the full console/PC release will be. But fun to pull out and play if you have 5 minutes to kill.
I haven't played it so I can't say gameplay wise, but what I can tell you its just a marketing machine for the actual game. Its brilliant as a marketing tool to get some of the game concepts in front of gamers and also get some familiarity with the brand name before release so its more known and less an unknown.