ArbitraryWater: It's not nearly as bad as people give it credit for. Unfinished, bland and sort of mediocre? Yes. But "Gouge your eyes out and write nasty things on the internet" bad? Not really. In fact, the only reason I didn't finish it was because it decided it no longer wanted to run on my computer. It has its moments.
Engine (and compatibility issues as result) was main factor which made MM 9 very bad. It was ok game (somewhat short for being MM), but it was poorly optimized and had some major scripting bugs. Gog version has most of it fixed, including compatibility issues, but engine still feels like it is in Beta. Game isn't actually all that bad if to close eyes on engine and try to avoid scripting bugs :)
ArbitraryWater: The biggest obstacle to progression in the game isn't experience, it's money. Training is absurdly expensive at a certain point, so max out merchant for everyone and don't feel the need to invest much in learning.
I wouldn't say it so. MM 9 isn't as limiting on gold as previous MM. A lot of locations have quite fast respawns, which yield good return gold-wise. Age as stat was removed from MM 9. So player can take his time while completing quests (can farm specific areas with fast respawn, chain arenas, etc.)
About learning I agree. I didn't have it at all on my first MM 9 playthrough years ago. I ended up with very high levels after traversing through one specific mountain passage with Harpy-like mobs (Winged Aberrations or something like that) while completing some quests. That passage repopulates insanely fast, and winged mobs award twice as much as experience as they should due to bug :)
Also, MM 9 was only game after WoX which had true optional superboss, guarding the most valuable treasure chest in game. Q from MM 6 doesn't count - despite having a lot of HP he was quite harmless.