If you need room rear seat leg room, you should be getting at minimum a 5 Series. The 4 and 3 Series just feel cramped.
Compared to your run of the mill cars like Toyota, Honda, and such, this car is wide! You'll need to re-adapt to driving and making sure you don't hit the sideview mirrors of parked cars.
The wheels don't turn much either, many times when making a U-turn you need to come in wide or sometimes are obligated to do a 3-point-turn.
The maps navigational system leaves a lot to be desired. No real-time traffic updates, they are delayed. Street construction or closures are NEVER updated. In San Francisco, they have been working on a huge street project (Van Ness St) which is about 30 blocks long and they made it so there are only 3 places to make a left turn. The BMW maps never updated this.
Also, when going to shopping malls that are away from the city and require freeway access, it will drop the pinpoint in the middle of the road, it doesn't tell you if it is located on the left or the right side. The same happens as well in the city, but not as much.
You have to pay extra for features like front heated seats, power adjustable seats, camera option and other simplicities that other car companies already provide as standard pkg.
The car is smooth to ride, though they use RFT (Run Flat Tires). I recommend using regular tires if you need an incredibly smoother ride.
Though the benefit of RFT is that if your tire punctures or is damaged, you have about 100 miles of driving left as long as you drive at around 50 Mph.
In the end, this car is a joy to drive and is incredibly comfortable; 306 HP is more than enough to have some fun and compared to other cars, the 535i looks fancy.
If you want more power, look into the 550i for 445 HP.