Briefly: very poorly organized and over prized tour. Stay away!
We went to their vesuvio trip as they told that pompei was closed for a couple of hours and the trip would take two hours. They sold the trip with a promise of a guided tour.
Trip started 10 min late. Not a big deal. There wasn't seats for as in the van, illeagal ! First van dropped us at another office of the company and soon another picked us up. The second van drove around the city for a good half an hour. It also went to the office where we started our journey with the first bus. When we finally arrived at the vesuvio, we were told that the pickup is after 45 minutes. It took us 20 min to walk up. The guided tour starts every 15 minutes and takes 15-20 minutes. This leaves as only 5 minutes to walk back even if the tour happens to start just when we reach the top. We could not take the tour as there was no time.
The van back to pompei was half an hour late. It dropped us at the highway intersection and told us to wait another car to drive us (10 people) back to pompei. We went to the first car, and the rest were left behind. Entire trip took 4,5 hours instead of 2.