Does anyone know a lot about the SMG in the E46 M3? I've done quite a bit of research on it as well as test drove one. However, I need to know some pros and cons. I haven't really been able to find any facts, just personal opinions.

First of all the M stands for M not manual.

2nd since you really weren't specific in your question....here is the authority on SMG: http://www.leo.nutz.de/mybmw_2.htm

HTH,
Bruce
95 M3
89 M3 2.5