Mage is... well, first, it's a White Wolf game, and WW has a wonderful talent for writing fiction that only seems to fail them when they're trying to write full fleged fiction. So if nothing else, it's a good mine of ideas.
Second, be very careful who you play with. WW games in general give the player more control and trust, with the downside being that it's all too easy for the player to utilize many cheap tricks and be world class in several areas. Additionally, in Mage every player is a minor Storyteller (read: DM), due to a very open ended magic system and the encouragement of Coincidental Magic (magic that "could concievably happen", as opposed to Vulgar Magic that only happens in high fantasy/sci fi. Think having a power line fall on somebody as opposed to having a lightning bolt jump from your fingertips). (As a side note, that may be something to steal, to a minor degree, for D&D games. The spellcaster tries to summon good/bad fortune on themselves or some other target, and depending on the results of a spellcraft roll and other DM decided factors, has some twist on that happen. Of course, that requires advanced players, and is a complete tangent.

)
As a game setting, it's kind of interesting. Reality is entirely subjective, changing to suit the beliefs of people. and different factions and alliegances of mages struggle to set their mark on it. "Default" characters believe that reality is too tightly tied together and that magic in its brilliant entirety should be brought back to the Sleepers (nonmagical people; think NPC's and you'll understand exactly how everyone sees them), as opposed to the Technocracy (Lawful types who think that everything should be safe, static, and predictable for everyone), Marauders (Chaotic types who think that the individual will is all important and are all insane), and Nephandi (stereotypical Evil types who either want to destroy reality or feed it all to demons). All while trying to be normal people in a world mostly like our own.
(And JFYI, I
do happen to like the game. It's just this side of impossible to find people who'll play it right, and played wrong the atmosphere is demolished. And for all the good I'll say about them, WW has a tendency to forget that its games are most likely to be played by gamers.)