Nothing really wrong with a 317 at all, and the 317/6 units refurbished by WAGN in the late 1990s were provided with a very nice interior indeed. Even those in original condition are quite acceptable as a commuter unit, though no doubt some will dislike the 3+2. The only other issue which some could have is that the motor car is quite rough riding and noisy, especially with windows open, but if that’s a problem then there’s three other carriages per unit to travel in.
From a reliability point of view the 317s are fairly average, and I’m not aware of them being particularly badly regarded by drivers. The single motor car setup could be problematic in autumn.