I really enjoyed it, but it's not on the level of Fantastic Four or Spider-man. I don't think it's essential reading for Marvel the way those two are. It's just good Captain America comics with him fighting AIM and Hydra, MODOK etc. Agent 13 gets introduced and starts a classic Cap storyline about her. Lots of great art from Kirby and Steranko. The very beginning is a bit dull as it seems Lee & co weren't quite sure what to do with Cap on his own, away from the Avengers. Then they dabble in telling stories about him and Bucky fighting during the war instead of stories set in the present day of the 1960s, and those stories are dire, but I think there's only about five of them, and after they're over the book starts to get good. If anyone stops reading there, they're missing out!
Overall, Silver Age Cap gets good much quicker than Iron Man and Thor (Thor takes the longest). Fantastic Four and Spider-man start off good. Ant-Man is never exactly good but I still enjoyed his epic collection for what it was. X-Men I can't be objective about enough to evaluate, the characters are too close to me. I haven't read Hulk or Namor or Shield or Avengers or Daredevil or anything else yet, but soon, I hope!
I'd lay good money on a reprint happening based on AoA just having received one, but I don't advise you wait. If it doesn't happen those prices could double by the time the film comes out. If you really want it, I'd bite the bullet and pony up.