details on how to claim the free Mass Effect 2 are here
the copy of Mass Effect 2 does not include the cerberus network code so no free dlcs which you normally get with a new copy of Mass Effect 2, you can still buy the cerberus network access if you want. so the game might be free but ea/bioware will make the money from people buying the dlcs.
this offer is useless for me as I already have the collectors edition which I got last year when the game first came out(not completed it yet tho, been meaning to go back and do so), been reading around and it seems you can give the code to some one else to use to download the free copy of mass Effect 2(so if some one wants a free copy pm me, first come first served

edit: well looks like bioware have decided to include the cerberus network dlcs in the free copy, appears so many people complained that bioware reconsidered.
p.s. dozen or so views and no replies?