It's a classic... RPG fans are obligated to play it.
FFVII is a landmark game for a variety of reasons. It's Final Fantasy's classic gameplay and flair for characters and plot, mixed with 3D graphics and a healthy dose of sci-fi.
Battle system plays similar to the RPGs (especially FF) that came before it... a turn-based affair with menu-driven battle commands. What really makes this game shine is it's cinematic feel. The music is unforgettable. There are many classic, memorable sequences in this game that will stick with you.
The Materia System is FFVII's level-up gimmick. Personally, I dislike it. I don't see the cool factor in leveling up these marbles that give me magic powers, to be honest. I really like my characters to have abilities of their own. I choose not to get wrapped up in the details, though.
Also, my other main complaint with this game is that sometimes, the character designs and dialogue will just lay a goosegg. Almost no game is 100% serious... but sometimes I found the odd choices for characters (Cait Sith?) and some goofy dialogue to distract from the serious nature of the game. It's hard to criticize though, as this was the style back in the day. Barret serves as comic relief a little too often for my taste. The anime art style is definently matched in tone, for better and worse.
So... is this the best game ever? Not really. Though I like this game a lot, there are other role-playing games I like more... including many other FF games released both before and after this one. My opinion is at odds with many many people, however. Ne'er speak ill of this game on any forum or within 1000 feet of a college campus. I have been able to wade through the sea of politics surrounding this game and enjoy it. FFVII is a landmark game, and a real treat that just sweats "classic".
The Verdict:
Every RPG player must play this game. It's obligatory. For it's time, it was revolutionary and it's fanbase is enourmous. You should at least be curious enough to find out why there were 5 people dressed like purple Goku's at your video game store yesterday.
+Cinematic presentation that was revoluionary for its time
+Classic Final Fantasy gameplay
+A good story with some classic twists
+Cool real-time strategy minigame
-Goofy character designs
-Materia system doesnt fit with the setting at all