Not sure what I expected but it looks like he got the Marvel workout in.
I never understood this character's popularity - anyone want to explain it?
(I mean the Marvel character)
How so? I mean I read some comics and he never stood out to me as being particularly memorable.
He is one of my favorite characters, if nothing else read Starlin's Warlock run from the 70's, 80's though you need a reading guide since due to cancelled books/fill ins/other roadblocks a lot of it was told in whatever book Starlin was writing at the time. But most of that stuff, but especially Adam, Thanos, and Gamora fighting the Magus and Church of Universal Truth is excellent, and a lot of the MCU as it is wouldn't exist without Jim's work.
As for Adam himself the most important thing to know is he is the opposite of Thanos and it makes them working together even crazier and memorable since they are natural enemies and exist literally to be each other's opposite and enemy since Adam is Life's chosen Avatar and champion the same as Thanos is Death's Avatar and Champion. Which as an aside is why I always get pissed about people minimizing it to "Thanos has a crush on death" which while he does (or more appropriately did) have romantic feelings for Death he is her chosen champion and avatar, and him wiping out half the galaxy was not "he wanted to impress death because he had a crush" but what she had actually gave him a mission to do in the first place and instead he fucked off and gathered the stones and made the gauntlet and when she got pissed he did the snap to accomplish that goal but it was already too late and then he claimed he did to be equal to her and worthy of the love between them which just pissed her off more making a bigger rift between them and killing any feelings she had for him.
Also don't know how they are going to explain the gem on his forehead due to the stones being destroyed but if you look closely in the picture he does have a gem on his forehead.