I'd say it's overrated and I'm a fan of the series. As far as gameplay, level design, presentation and boss fights I give the Tanker part of MGS2 an A. The Shell part gets a C-. Yes, maybe I didn't like the switch to Raiden, but his character wasn't what made the game fall apart for me. The game just wasn't well thought out, and almost seems rushed. I had the same problem with MGS4. Very strong start with Act 1 and 2 and then runs out of steam with only a few cool moments here and there towards the end. To each his own though.
"you dawg i heard you like watching TV so i put a TV in your TV so you can watch TV while you watch TV" --- the_great_tidus on 360 TV