I just finished up the DLC for the first time this morning after winning the main game last weekend. Whilst it was quite brutal at times, I'd have to agree with other posters regarding the very bad opening dungeon design. At first I found it novel, but after several instant deaths and loading screens, the novelty factor soon wore off and it simply became irritating.
Curiously, the first boss fight with Perren was one of the biggest challenges in the entire game. It was a real test of mana management more than anything else without having potions to chug and having to use regular weaponry/non relics again. The first fight with an Inquisitor was also a battle of attrition, but with good spell selection, I was able to overcome those groups.
The long arduous fights through the Summer Palace were fairly manageable once I could retreat back to a square that prevents flanking. The Runelord's fire rune spell and the Blood Shaman's Tsunami in combination proved quite useful in slowly chipping down the health of mobs. Another extremely useful survival measure I found was having the alchemist as a hireling. The ease of access for more mana definitely made the later fights much simpler. The last fight was tricky - lost my mage a couple of times due to the nasty light damage, but eventually with the right buffs I got there in the end.
Attached is an image of the classic Might & Magic winning certificate. My party was level 34. There's a couple of quests I didn't do (Temple of Meow - didn't feel worth it this time) and I still managed to end up with over 80,000 gold at the end without really much to spend it on, a slight misgiving that I also had the first time through the game. Still, I had much more fun with this party and the additional challenge factor up until around the end of Act III was great, after which this party became quite the power-house and literally stomped its way through the Tomb of Thousand Terrors.
Final party breakdown and comments:
Windsword (With the plethora of mana at hand, using the high end warfare abilities like furious blow and flawless assault was decent in the end with a two handed relic weapon. Overall, the weakest character by far. )
Blademaster (Incredible damage dealer. I really pumped destiny early for the increased criticals and obtained grandmaster in dagger, dual wield and dodge. She was a bit of a glass canon at times with some of the monsters who could reflect damage, but ultimately this character was the melee killing machine of the group. Carnage was quite handy in a tight squeeze.
Blood Caller (GM in Earth, Water and Air Magic. Extremely useful and powerful character; the heart of the group with regeneration and liquid membrane saving the day many times. Mace master was useful for the stun effect too. )
Runelord (GM in Fire, Light and master in Prime. Another very powerful character. Fireburst wreaked absolute havoc mid-late game. Celestial armour is also simply a great spell for the entire game. )
In conclusion, whilst the DLC was average at best, overall I'm still quite happy to have played through this game a second time. It makes me consider testing other classes or going back to other M&M games and indeed, reminds me that the only game in the series I have yet to finish is MM2.
Edit:
All M&M certificates (6-10) have a score which generally reflects the amount of content completed in the world as a whole. There were at least three dungeons and a couple of quests that I didn't finish to completion but the party was plenty powerful enough as it was.