Besides a '79 VW Beetle Cabrio, my Euro '85 E24 "dogleg" 5-speed has been the most reliable car I have owned. I'm its original owner and have never been stranded on the side of the road with it. Mechanically and in general, it represents the highpoint of superlative German engineering, craftsmanship, and quality.
The noteworthy feature of this car is how timeless its design and lines are - Paul Bracq architecture that will never go out of style. To this day, this car turns heads. I also own the predecessor model to the E24 6-series, a Euro '75 E9 (3.0 CS Coupe), which is also a truly beautiful car, but mechanically the E24 is far superior. It has a perfect combination of handling, braking, power, comfort, steering, and class. There are other cars that are quicker, stop faster, handle and ride better but I can't think of another that combines so many positive qualities into a single car.
Admittedly, I have been very indulgent about maintaining it. Parts and service have never been inexpensive. But for something as beautiful, elegant, stylish, and these days, as rare as this car, I'm ok with that.
I encourage you to have the car thoroughly gone over and assessed by a very competent BMW mechanic as to it's general condition and what it might soon need. Be especially mindful of rust. For me, that would be a deal breaker.