It's without question the only game I've replayed as much as the MM series. Party-based, big world, lots of race/class options & replayability. Never played Wiz7 but I believe it's as good (for its time).
The only unfortunate thing about Wiz8 is the game plays real time until combat, at which point it switches to turn-based. And it does this when the enemy chooses to engage you, sometimes from a considerable distance, not just the battles you want to fight. Which means you fight every. Single. Battle. The game wants you to fight. No punching through easy battles in RT to get on with things, and no running around the map avoiding battles you can't be bothered with. You also can't save during combat, so no saving after every lucky hit you get and reloading if it goes badly. The number of battles in Wiz8 I've played for an entire hour only to restart makes me cry.
With some specific battles placed in specific areas, this also makes it somewhat more linear than MM simply because you can't access certain areas until you're powerful enough.
But it's a solid game, highly recommended. Like many of these games I guess, the endgame gets a bit boring because you're way powerful enough to win, and the forced combat aspect of Wiz8 makes this more tedious. But despite all that, it's got a great story, clever system and some really unique elements