I just finished playing MM6 and it was a lot of fun and a worthwhile game to replay. That said, here are my criticisms of the game:
-The first 2/3s of the game is paced fairly well. But there are a few bottle necks where it seems like no matter where you go the fights are too difficult requiring that you go grind in lower level areas. Sometimes I didn't mind doing this but sometimes it was annoying.
-Gear drops are useful for the first 2/3s of the game but then drastically drop off during the final 1/3. There should have been more gear tiers given the length of the game. You do start finding relics and artifacts during the last 1/3 of the game but a lot of the excitement of gear drops wanes during this period. Enchanting helps, but enchanting is a monotonous exercise in saving and reloading until you get an enchant you like.
-Condition removal spells should just affect the entire party when they are cast at Master level. Having to constantly micro manage conditions for individual party members really becomes a drag given the length of the game.
-Some of the non-combat spells should really somehow be usable by any party member. I got master level in repair item with 1 of my characters. But this is a pain in the last 1/3 of the game where there are 100s of fights with monsters who damage equipment quite literally each combat round. You end up in an exercise of constantly moving equipment, one by one, to the character who can repair so that he can repair them, then moving them back, then re-equipping them on the toon. After you've done this a few hundred times you start considering to just fight mobs who break items while naked. The 'Blessings' concept of M&MX sounds good to me after having gone through this with M&M6.
-It was unclear to me why I couldn't get master level in light and dark magics. I had to consult the internet to find out that my karma affects had to be at certain levels. Then I had to find out on the internet how to get those karma numbers moving. I suppose if I had read more of the NPC dialogs that provide lore for the world I might have picked up on this myself. So this is partly my fault but it could have been clearer through the game too.
This is an awesome website to help you along while playing by the way.
-Castle Darkmoor & Dragonsands. Oh how I loathe thee. Darkmoor for it's 'eyes' that constantly dispel your buffs and Dragonsands for the dragons who break everything during each round of combat. Conceptually I don't mind dealing with the ideas of being dispelled or having equipment break. But given the number of mobs that must be dealt with and the frequency of dispels/items breaking you are lucky if you haven't ripped all your hair out by the time you get through it.
-Some of the general quests should have been better explained. The Arena quest, the seer quests (to travel to certain locals and pray at alters during certain months of the year for permanent buffs) to name two. I never finished Lord level of arena, even in late game at L106. Just not dealing with an arena of Golden dragons after playing Dragonsands... no thank you had enough.
-At a certain point along the main quest line, near the tail end, quest entries in your quest log stop and you play the final parts of the game with no quest whatsoever. This was a little confusing about what to do. Not sure why they did the quest log so well for 99% of the game then totally dropped the ball right at the end. They were likely in a rush to ship...
I re-played M&M7 last summer so I am now moving on to M&M 8 - an installment I never finished and I'd like to actually finish M&M8 for once.