When I played with a full party, it meant that I had to actually sit and stare at the screen for longer since turns were all mixed in. The thought of playing with more than the current party size sounds like a nightmare to me. :P Soloing at least made it possible to do other things not game related while the enemies took their sweet time to do a lot of nothing. I will be happy if they can speed this up. At least in proper DnD there is other stuff going on while people are deciding what to do in a turn, and it is not boring.
Maybe this tedium is a common thing with turn based games? This is the first one I have played, normally I play real time games and occasionally RTwP, so perhaps it seems slow for me since I am used to having to make quick decisions in combat.
I agree there is a lot that is broken, namely stealth play. I will still solo at least one playthrough just because I like different challenges but would prefer to play in a normal party if they speed up the combat.