The more I play it, the more I like it.
To be fair, the story is all, and I mean ALL over the goddamn place. But I think that's part of why I like it. Huge characters and arcs are often dropped within hours of introduction. The ending and the antagonists motivations still make no sense to me, after having played the game probably 4 times through now. The story is probably the most "Metal Gear" of the Metal Gear games, if that makes any sense.
To Kojima's credit however, all pieces and bits and bobs are wonderfully engaging and interesting, and no matter how ridiculous things get there's always a grounded sense of reality and gravity to every situation.
The gameplay is great, no question. The controls take a bit of getting used to, like any metal gear game, but that's because they account for a huge variety of stealth moves and contextual situations on a relatively small number of buttons.
It plays differently than 3,4, and Peace Walker in a few ways. For one, your footsteps are never heard, and there's no camo. These little things in general make it a bit faster paced and acrobatic game.
As for Raiden, I like him. He's a good character, and has arguably development than Snake typically does. I also like Rose, where some find her annoying.
MGS3 is probably my favorite Metal Gear game, but 2 follows closely behind.