Speech is very important. I think it's a sort of a rule of thumb that you should always tag speech, because you'll want to get it up to 100% very early in the game. Along with intelligence, it's a very important characteristic for any normal character. (I reckon you don't need speech for a guy like Torr since only other retards understand him anyway) Also, if you like being very tough and evil, never making any friends and always shooting your way through social and other situations, then I guess you shouldn't bother with speech.
It affects many quests and npc reactions ... even dialogue options, I think. (If you have low speech and you have to lie, your char will only have options like "Uhhhh... eeerhh... I didn't really ... umm... you know..." instead of "Yeah, sure - I did it just as you asked!") Correct me if I'm wrong and fill me in if needed.
