We have one on a BX that has now been through all Four Seasons.
Pro's:
No Trailer to drag, more maneuverable.
Has enough suction to pick up leaves in the Fall.
Entire unit is supported by its' own legs in storage.
Less than 10 minutes to mount or remove.
Quiet, compared to one with a separate engine.
Less maintenance, compared to one with a separate engine.
Con's:
Less capacity than a trail behind unit.
Had to add front weights to maintain steering on hills when bagging wet material. May not on big 'ol B tractor.
Fairly expensive.
Overall, I am satisfied enough to feel good about the purchase and do not wish I had something else. I only use it in the Spring and Fall. If I was putting it on and taking it off every weekend, I might be happier with something that only required a hitch pin to hook up.