As far as fifteen year old high-ish end euro performance-ish cars go, it's a cake walk and a bargain to boot. I'd drive one before committing, the clutch and MT are not bad, just weird. There is a delay valve you can remove from the clutch to normal it up some but it's still a big BMW with a stick and a v8, I like it but others have not. You got good info on the cooling sys, chain guides, electrical bits being trouble spots. It's old enough to pay attention to the clutch and suspension rubber, they kill the torque strut in the front pretty regular from all the weight and tire, there is an m5 upgrade I'm sure.
I'd either have a car-payment budget for the first year if you have to have it serviced, or about half that if you can DIY, but it's really not bad as far as such things go. Gotta pay to play as the saying goes.
Those cars are a point and click bullet. It will invite you to go-to-jail speeds, quietly, quickly, on any given street. It's not that it's crazy fast, you'll want more after a few days getting used to it, but it's so smooth and easy and unobtrusive to bust triple digits. It's not crazy fast by today's standards but it's got enough, and if you have the budget it's upgradeable.
I'd want an M5 too, but it's a whole nother ball of wax maintenance and such I assume, never had one.
edit: those are comfort seats, not sport seats(which would be manual and awesome).
Beware people not understanding what package the car has, that might be the m pak with
the comfort seats added, or it might just have some wheels on a regular model.
I'm pretty sure that's not the right steering wheel either for M but it's been a long time
since I messed with em so can't be positive.