I owned a 1998 Rialta. It had a VW VR6 gasoline engine and it ran really well. It is NOT a B, it is a class C as described by the Winnebago literature and meets the definition of a C. Some might call it a B+ since it does not have the cab over bed, but they would be wrong, it's a C. Now that that is out of the way...
We liked the performance, gas mileage, and features of ours. We had the twin bed FD model. The only feature we could never get used to was the shower/bath combination, having to pump the shower water into the holding tank, pull out the walls to make the shower, etc etc.
When it came time to get new tires, it was a struggle locating tires that would carry the load. Things may have changed but back then the only ones that met the specs was Continental and they were hard to come by.
The VW parts were flawless. However, we had to find an independant foreign car shop to work on it. None of the VW dealers in the area would touch it.