These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Captain America: The Winter Soldier
Broken Base: Not a big example yet, and it seems to be a Vocal Minority, but given the identity of the Winter Soldier, fans of Avengers comics or fans of the films that did research will already know it's Bucky. Because of this, there's some fans who believe this means Falcon won't be getting as much screentime as they want.
Many fans are elated at the inclusion of Natasha as a major character. Others, however, are upset that her involvement seems to be effectively subsuming the role of Agent 13.
Hawkeye's fans are annoyed for another reason- Natasha has already been in movies other then Avengers, whereas Clint was shafted for screentime in it, leading to some saying they wished Natasha could take a back seat for Clint.
There are also some annoyed that Natasha is playing second fiddle to Steve instead of having a film of her own.
The Winter Soldier plot being done so quickly, without Steve having at least one film to adjust to modern life and form solid relationships with Sam and Sharon.
Cap's new uniform for the film has also gotten a mixed reaction, with some declaring it to be an upgrade over his costume in The Avengers, and others lamenting the removal of the red-and-white stripes from said costume.
It Was His Sled: The Reveal of the Winter Soldier's identity was an 8 year old spoiler for comics readers by the time the Winter Soldier film came out.
Some Italian fans compared Winter Soldier to Adam Kadmon. He's also been compared to Raiden, thanks to his mask, Super Reflexes, and cybernetic limbs.
"The Helicarrier's becoming the Enterprise," in a reference to how the thing keeps seeming to die whenever we see it.
Ship-to-Ship Combat: Some rather rabid shippers are already voicing opposition that Bucky may become a potential love interest for Natasha (Black Widow), thus sink their hopes for a Clint (Hawkeye) and Natasha relationship. Though this assumption isn't without some merit, due to Bucky and Natasha having actually been an Official Couple in the comics.
And now, with the emergence of on-set photographs showing Steve and Natasha kissing, both are threatened by the emerging ship.