if your going to drive it daily. get manual. if it's just a weekend car, smg. the hydraulic pump on the smg will give you an issue at some point.
try to get 2004+ models (led tail lights) as the early 01 and 02 m3's had the rod bearings recalled on them.
no electrical issues that i know of.
subframe is hit and miss.
no real problems but try to get as much maintenance covered before you buy it especially the valve adjustment if you could.
Current:2013 Candy White VW Golf TDI
Sold:2004 Silver Gray M3
Mods: Dice Unit, EAS Angel Eyes, Painted Reflectors, CSL Diffuser, Smoked Corners, PSS10s, 15mm Front and 10mm Rear Spacers.
Gone:1990 Brilliantrot 325is
Mods: Alpine speakers and HU, Euro Projectors, Magnaflow Muffler, Euro Smoked Tails and GC Coilovers.