If it's crap ... We'll tell you
DAMN! Those are some of the best and unique Cover Arts for films I have EVER seen! It kills me that neither the separate Blu-Rays nor the posters even come close to how good these look. Now as for the "Bonus" Disc I don't know if it carries all the extras from the separate Blu-Rays or only contains new extras. I hate the idea of even passing this set but this'll need more than awesome artwork for me to consider getting this.
For those wanting just the Avengers the best set to get is the Target Exclusive 3D or 2D Blu-Ray sets. Those will have a 90 minute documentary called "Building a Dream: Assembling the Avengers". This will tell how all the individual films connect with the Avengers using exclusive footage. I am skeptical on how good or bad this documentary will be but the Target set is still recommended.