First time posting, been lurking for a while...  We travelled from LA to Orlando for a trip this past week.  I was really hyped up for Gringott's and the whole experience.  We were at the parks for 3 days, staying at the Portofino starting last Thursday, and ending Sunday.  We enjoyed IOA at a slower pace on Thursday, but migrated to Diagon without a wait later in the day.  At one point Gringott's was 120 minute wait, which I was up for, but the rest of the party was not.  Loved everything else.
Friday, we get up super early in a hope to get on Gringott's.  I left at about 6:00 AM with my son.  We walked to the park, and followed the line, which ended up in a switchback outside of Diagon at about 6:20 or so.  The rest of the party was further behind.  They ended up stopped around the MIB area.  My son and I got in to diagon around 7:15, and the entire queue was basically in line for Gringott's.  The TMs were telling everyone one that Gringott's was going to have a delayed opening, yet everyone still queued up.  We got out of line right at the main entrance, waited for the rest of our party, and enjoyed Diagon for quite a while, then exited the area.  We enjoyed the rest of the park until around 2:00, when we went back to Diagon...  At about 2:20 we got in the "120 minute" queue for Gringott's.  We were on the ride in a little less than an hour.
First impressions...  great ride, great effects, but shorter that I expected.
Saturday, around 3:20, when the wait time was around 120 minutes again, we got in the queue with more of our party that missed it last time.  We were next to load at 4:20 when the ride broke down.  About 10 minutes later, after they had run 6 or 7 empty carts through the ride, we loaded and had a great ride.  
Second impressions, better than the first, amazing ride, still too short.  I also realized I saw the "kuka arm screen removal" or "KASR" both times due to lack of fog effect.  I think that was the only thing missing both runs.  If that was working I think it would have made a huge difference in that next to last scene.
TLDR; great ride! too short..  wait times advertised are significantly less than actual (50% less?).  It will be too long before we are there again...