Potential M3 buyer

Hello there,
My name is Mikael, I currently ride in an AP2 s2000. It's beautiful blend of handling, simplicity, and power. S2000 are amazing cars. The unique features of the car attracted me to it for many years until I finally had the chance to get one. I have invested thousand of dollars into the car to make it the way I wanted it too: rims, hardtop, exhaust, intake etc...l
Couple years later I find myself looking at every E46 M3 I see. In my opinion, The simplicity of the E46 body matched with a high revving v6 is pure beauty.
I'll hopefully be getting one within the next 12 months or so I'm gonna hold onto my s for little whiile longer while I save a little more cash or until I feel ready. My question to you guys is, when I go to buy are there any specific things I should look out for? Any problems or issues that are common with these M3s that I should look out for? Any members on here have owned or driven both an s and m3 and can give the pros and cons of both. Any help or. Advice would be greatly appreciated.