I'm currently about halfway through the game I think (not counting the expansion, I just got to Dorn's Deep Chapter 4.
I made a thread asking for tips for party composition last week. In the end, my party is:
1- Undead Hunter (dual Wield) lvl 8
2- Berserker lvl 8 (very close to 9)
3- Sorcerer lvl 9 (very close to 10)
4- Cleric lvl 9
5- Cleric/Thief (Multi-Class) lvl 8 and 9
6- Shapeshifter lvl 11
I had never really played a Druid in the BG series aside from Jaheira and she wasn't a pure one nor with a kit and people said that Druids had stronger spells in IWD. I'm happy with my decision. My druid levels quite faster than the other party members and does have several decent spells that my Clerics don't have access to (notably some AOE spells that do well coupled with Entangle).
I don't have the Greater Werewolf form (lvl 13) yet so I don't know how much better it is than the regular one. However, the regular form seemed really good early game with its strength set at 19 and 2 attacks with good dmg compared to my other characters that didn't have magic weapons yet (so the dmg and THAC0 wasn't as high as it is right now). It wasn't really stronger than my 2 other melee characters mostly due to the fact that the Berserker is Half-Orc (19 str) and the Undead Hunter had 18/99 str (lucky reroll) but it would definitely have stood out more if I didn't reroll or abuse racial bonuses (like Half-Orc 19 str chars at character creation).
So early game, it was a decent melee with a few support spells so I could use these and then morph and frontline. However, as the game progresses, I get more and more spells (and better ones) so I'm using the Werewolf form a lot less. The other two big problems I see with this form is that I think that the attacks do not count as magic weapons (not even +1) so that any mob that requires magic weapons to hit are basically immune to the Werewolf attacks while my other party members can all damage them. The other big problem is that the THAC0 is just too weak to be a good melee it seems.
Right now, my Undead Hunter, Berserker and Sorcerer are all fairly close to leveling (so their THAC0 might get reduced even further) but they still have much better THAC0 than the Werewolf despite being 2-3 levels lower (except for the Sorcerer but he's meant to cast spells more than attack with weapons anyways).
The Undead Hunter with Dual Wield has 6-9 THAC0 (less vs Undead), Berserker with +3 two handed sword is at 4 (2 when using Rage), Cleric is at 10, Cleric/Theif is at 11, Sorcerer is at 13. The Werewolf keeps the same THAC0 when shapeshifted (11).
Overall, it seems like the Werewolf can already hardly hit anything anymore and I'm only lvl 11 not to mention no magic dmg on attacks (making it unable to damage several types of monsters) and no way to upgrade its damage since it doesn't use weapons (no scaling). It feels like it's a decent melee for maybe lvls 1-6 and then it falls far behind. It's too bad because I find it quite interesting for a class and enjoyed having a hybrid spell caster that could switch into being a strong melee frontline. So far, the spells my Druid has to self buff can't really help its THAC0, it's mostly survivability buffs (like Iron Skins or Entropy Shield).
Am I supposed to rely on other party members to have buffs to help its THAC0 and reduce enemy armor? Is there something I'm missing here? Is the Greater Werewolf form a lot stronger and makes up for it while the regular Werewolf form is more useful for the first few levels of the game?