Minibus transfer was good, picked up very near our hotel. Once we arrived at the boat we found that this is actually a tour with 80+ guests, despite the TripAdvisor description stating "This tour/activity will have a maximum of 15 travellers". This is deceptive and really should be removed from the Additional Information section.
We went anyway, the boat was crowded and there was just enough space to sit as long as plenty of people sat on deck on mats. There is only enough shade for less than half the passengers, and you'll be on for 8 hours, so prepare to get cooked if it's a hot day. Lunch was basic but fine for a boat, chicken or fish with some pasta and salad options. All soft drinks and beer were included in the price, which was a nice surprise, there were spirits and cocktails for sale on top. Did have a decent toilet too.
We went to 3 sites, first to paradise bay on Malta, then a name I forget on Gozo, before finally reaching the Blue Lagoon in the afternoon. The first two stops were much less busy, and quite nice for swimming, but just bear that in mind, this is not necessarily a "full day at the Blue Lagoon" experience (which would probably be too busy anyway). The boat had steps to get in and out of the sea, and snorkelling gear for hire for a couple of euros for the whole day. You might want to bring floats for kids or weaker swimmers though, at some stops the water was a few meters deep and you would have to tread water waiting to get back up the boat steps.
The optional speedboat trip at the Blue Lagoon was great, shows you a bit more of Comino and very exuberantly driven. The lagoon itself is so massively busy that you were better off just swimming by the boat rather than trying to walk to the "beach" area.
Overall it was a decent trip, you get a nice cruise up the coast and some decent spots to swim. But it is crowded and unshaded, and slightly deceptively described here. If I did it again, I'd pay more for a proper small group trip, or just get one of the big red ferries where you're guaranteed a seat and some shade.