Its a bit compromised car, as I've also been giving it (1ser coupe) a good look over, as I really liked the chunkyness and stance of the car from day one that it was released, and from what I hear wrt handling, the car is very chuckable in the corners, reminds me of the E30 2door, and actually had a look at one over the weekend.
From what I can see you can buy an E92 for similar money if you shop around, as even though it is a 1ser, these cars where pricey when they where sold as new, so a used 1ser coupe buy now is still what can buy an E92, which is a bit more car and features. The fuel tank might be an issue, with only a 53L vs 65L in the M3 as well, with hard driving you'll be filling up often.
If you like the body style, have you considered a 120d coupe, which is more economical, & awesome on the open road?
Some things to consider:-
Rear leg room
Fuel tank
Boot size
Lack of spare wheel
Boot size with space saver wheel
Lack of electronic climate control
These are some things I picked up so far.
Thanks