No complaints, the trip was all OK. We were met by a chap called Julien who seemed very helpful and after a short walk to the gondola station off we went. We had a full 45 minutes from start to finish - we returned to the same start point, shared with some nice folk from US and Australia. Wonder slightly if I'd have done better just booking it locally (the rendezvous was quite a haul from where we were staying) but I've no complaints - payed a few euros more for doing through Viator but on balance probably worth it. Would recommend to new visitors like us but next time we'll probably fly solo. Bottom line - you can't beat seeing Venice from a gondola.