I'll take the heat on this... I didn't love THE FIRST AVENGER. (ducks rotten food and large stones)
Now... That doesn't mean I hated it or thinks it is bad. I like a lot in the film, and there is some great stuff. What do I really like?
1. Evans. He has owned this role from the first time he shows up on screen. He makes you invested in Steve before he's given the serum, abetted by the fantastic CGI that makes a specimen like Chris look like the prototypical 98 lbs. weakling. He just works like gangbusters on screen as a simple moral guy that wants to do good as he sees it. After he gets enhanced he makes you remember that inside is still that scrappy guy willing to jump without hesitation on a grenade. They hit the jackpot getting Evans at at his young age we are seeing a great old school leading man in the making. Anyone that doubts his chops should look at his performance in SNOWPIERCER.
2. Haley Atwell as Peggy is great in another performance that evokes old school Hollywood. I could easily see her in classic films from the 40's and 50's. Stylish and beautiful but with strength and charm she made a character that was actually a bit of a foot note in Marvel Comics history and made her a fan favorite. Hopefully Hollywood can find something to really take her career to the next level.
3. The guts of the film, by which I mean the rest of the cast. Everyone is pitch perfect in their roles: Zola, Skull, the Col., Stark and Erskine all make for good characters. This is important as it can be a deathknell for some films of all they concentrate on is who is cast as the lead or leads. The "guts" is really important to a film and the guts are solid in this movie.
4. The production design. The look of Cap's costume, the Hydra outfits, the designs of Hydra's tanks and equipment... All top notch. After Thor, I would say that the next highest hurdle Marvel had in adapting their material was with Cap, and they did it with flying colors.
All that said... I do feel there are some big weaknesses.
1. Bucky. Sorry... I would have preferred going classic with Bucky. I don't think that making Bucky Steve's "big brother/protector" added anything and I really feel that their relationship felt thin to me. Adding insult, just as we get to see more Barnes and enhanced Steve interact (spoilers) he's gone and... It didn't really register for me. It fell flat. This is not just a weakness for this film, I think it detracts from THE WINTER SOLDIER. I DIDN't feel their connection in TFA so I wasn't invested in it in TWS. This doesn't ruin the movie but... Yeah, points shaved off. And the add on scene of Bucky and Cap after Steve's mom's death in TWS didn't do much for me either.
2. The rivalry between Skull and Cap feels thin as well. In fact this is a problem with Skull in the film. Like Spacey in SUPERMAN RETURNS, Weaving feels underused, or not given the strongest material. Rather than meeting once before the finale, Cap needed to clash with Skull at least one more time. Skull should have done some more acts to show the depths of his depravity. Sure, he bombs that village to get the cube and kills it's guardian, but after that he kills more Nazis and Hydra and takes out some red shirts. There should have been something heinous he does that Cap witnesses or sees the aftermath of. In fact, it probably should have been Skull that took out Bucky.
3. The action in the film is a bit by the numbers. Cap really needed to move in a more dynamic manner. This was improved upon greatly in TWS. Still, I would have liked to see perhaps some training of Cap to get across the idea of his full capabilities. It's like they make a point to say the character of the man is more important than the serum but suddenly he gets the serum and he is the world's greatest hand to hand combatant and a tactical genius... I would have liked to see that develop, rather than have it just happen. Which brings me to...
4. The big time jump where Cap and the Howlers' campaign in the war is seemingly covered in a standard montage. What should have been an epic WWII pulp super hero tale suddenly gets truncated into less than five minutes. This film needed a longer runtime in my opinion. Then there is time to expand on all the issues I've brought up, which impacted my overall enjoyment.
Again, I don't think any of this makes the film cross off into "bad" territory but there is lots I find lacking. I still think it's a better film than IM2, THE DARK WORLD or even TIH, but in the end I think TFA is good if pretty uneven.