Good lord, what a game. There's really nothing quite like the Metal Gear Solid series. The way the gameplay and story meld together in such a way is just special, and had never been replicated in quite the same way (aside from MGS 2 and 3 of course). This game has an amazing story, good atmosphere, and gameplay that is decent most of the time but aged like milk (specifically a few of the bosses and some combat encounters). Psycho Mantis, Sniper Wolf, Vulcan Raven, and Rex are some iconic boss fights that still holds up as thrilling engagements. Liquid's three phases and "Deepthroat" (hehe) were downright frustrating though. Especially that awful turret section at the end... protip: use first person view for that turret section.
There were some memorable sections as well, like the torture section that actually tortured you, the player. This was brilliant, if not physically painful. There are also sections like the comms tower chase, which was a memorable moment for the wrong reasons because they bring out the game's jank in full force.
As an arcade stealth game, it's serviceable, but there isn't as much stealth gameplay as I remember there being. It's mostly an action game against a myriad of bosses and crazy encounters, interspersed with the occasional lackluster stealth section and tedious backtracking. It's especially poorly paced in disc 2, when it's just balls to the wall action until the game is over. Overall, a great game, but I prefer the sequels.