My son and I went on the trip over Easter. He loves boats of all sorts and though for me, working in Belfast Harbour, it was a bit of a busman's holiday in what I saw, it was a terrific experience.
The rib is powerfull and you get a chance to get a little speed up out at No.15 buoy. The staff and crew are very knowledgable and explain the sights extremely well. I understand they might be doing trips down Belfast Lough to Bangor in the summer - that would be a real blast!
Our tip: get down early for the trip and you can get the front of the rib - fabulous!