Had the SMG (in M3) for about 8 months now and I wouldn't take for it!
I had the same concern before ordering, but after using it a while I like it better every time I drive it.
It takes a while to get a SMG habit pattern, i.e., where downshifts seem natural etc -
but it is quick and a blast....
06 M3 Cnvt: CrbnBlk/Cinn SMG Nav Xenon HS HK LMBR