I have the Bobcat 48" version. It does a good job for what it is intended for which is small, close quarters compaction.
I purchased it for a townhome project several years ago. This project had full basements with 1 car garages at the main level. I calculated the cost of full stone backfill VS the cost of the roller, labor, time (10' high basement walls) and I could pay for the roller over the time of the job and save around $12K. (I would have some skid steer time involved in placing the stone and already had the skid.) Easy decision I purchased one.
It is a pad foot with a smooth drum shell, although I have never used the smooth shell. We used on-site material to fill the garages, 8" at a time with the roller on a T190. We had no problem meeting compaction after 2 passes. The material was chert (128 PCF), which is a quartz and clay mixture, that is compacted easily.
We also used the roller to compact the front backfill, which was considerable due to the sloping of the excavation to safely allow the construction of the concrete walls. Compaction was also important due to the only access for the telehandlers would be from the street, so the fill had to stand up to abuse.
But like Turbo21835 said, it is not a replacement for a roller on a large job, although it does have it's place. It depends on what you want to the roller to do.