Hotel Plaza guests have thier own bus system that is provided by the hotels themselves. The current company is Fleetwood Limousine (dba Bethany Limousine). They operate slightly older VanHool T940 and T945 motor coaches. As for thier condition... they're in average condition... not as clean as Disney busses... but nowhere near as filthy as Skytran... at least Bethany washes thier busses once a week I'd guess.
As for thier service... they run twice an hour out of the TTC, Epcot, Studios, and DAK... (some midday service is only once an hour)
They also have busses to Blizzard Beach, and Downtown Disney.
As for how good of a service they provide... *shrug* Couldn't tell you. The only thing I can tell you is Lane #26, twice an hour... lol