The special edition of Mass Effect 3 includes a metal case featuring both male and female versions of Commander Shepard, a 70-page hardbound art book, a limited edition comic by Dark Horse, a fabric N7 patch, and a 4x6 lithographic print featuring a one-of-a-kind piece of artwork. There are digital bonuses as well: the N7 Arsenal Pack, which grants access to four additional weapons; the Squadmate Alternate Outfit Pack, which adds new costumes for your teammates; a digital N7 hoodie for Shepard to wear on the Normandy; and a digital soundtrack. Perhaps the most novel addition of all: a robotic dog for you to play with while on board the Normandy. (Who says you can't play play fetch while saving the galaxy?)
The N7 Collector's Edition retails for $79.99, a $20 markup over the vanilla edition. Given the number of bonuses, it might just warrant the premium.