TotLM
I was surprised at the time it took me to complete this, for a 70mb download!
My Bard showed her worth again - defeating harpy sound attacks. But whilst there were some tough fights (the WereJackals, Spectral Guards and other adventurers), there was nothing that you shuoldn't be able to get through by this stage. The jelly trap had me going for a while

*****SPOILER****(highlight)
until I discovered acid damage kills them and you don't have to escape the trap!!! LOL.
Final thoughts
I am a fan of IWD and have enjoyed all of the add-ons. Sure, you're too powerful at the end but then the game is almost over so that's fair but it makes the add-ons exercises in building XP. It was fun hunting for anything better than plate mail when you were still level 6 or 7!
The mass battles are something BG misses out on. Hordes of shadow elves/goblins, trolls, minotaurs, sahaguin, frost giants. Awesome.
It came down to 2 things. Choosing your party and your tactics (and your party composition can dictate your tactics).
I still think mages are weak in IWD - any more than 1 and you run the risk of being swamped. But they are extremely valuable support. In that respect a bard is just as good, or an excellent way of sneaking in a "second" mage. Bardsong rocks. After level 12 or so, I didn't need healing spells.
A thief is not essential. I tend to dual a thief and often this removes thieving skills at the most crucial point in the game! But I survived.
After that I feel that choices are moot. Clerics, druids and fighers are all needed to hold their own in combat.
Having said this, I am trying a part of elves with 3 magic users so I'll see how it goes.