Let us give it a month and then let one of our forum members based in Edinburgh make a posting of how it seems to be running at the start of July 2014.
Purely by chance, one month on, had my first opportunity to use the trams yesterday afternoon (not in the peak). Impressions of four journeys (including out to Ingliston Park and Ride)...
Usage - reasonable levels - most seats filled most of time (not that there are that many!)
Comfort - Seats not bad; heat levels ok when seated but when standing, there was a lot of hot air near ceiling - I stood behind driver for one trip, and was getting rather hot and sweaty! It was a warm day and drivers were opening all platform-side doors at stops. There appears to be passenger-operated door opening, which was not enabled. I guess on a cold winter day, you would not want to open all doors unless you had to!
Ride quality - reasonable, and certainly a smoother journey than I have previously managed on any Lothian bus (which are better-riding than the local average). I found the braking slightly annoying - a sudden deceleration from about 2 or 3 mph, which I take it has to do with a different braking system kicking in?
Still some issues with signalling on Princes Street, requiring one driver to have discussions with control, and sitting at Princes Street stop for a couple of minutes before crossing the Mound junction. From in the tram, I couldn't see situations where buses were being impeded in their travel along Princes Street, but suspect that emerging from side roads would have been more of a challenge.
Ticketing - easy enough to use. I used a day ticket, but several people seemed to be confused by the unusual zonal system (two zones - the Airport and all the rest!) and the huge discrepancy in costs if you want to travel the last half mile! One woman whose ticket didn't cover her to the airport elected to pay an additional Standard Fare (£10) to cover the extra travel, but to his credit, the Ticket Services Assistant did explain to her the alternative legitimate ways she could do it for less. All the staff I met were extremely helpful and chatty.
Route layout - main thought was that travel between the Gyle and the Airport could have had a couple of minutes chopped off it by better routing! The sharpest bend is, I think, at the west side of Gogarburn tram stop, but there are others in the open countryside!