Very impressive.  Its sheer size make it quite a sight.  With the Munich clock, Sir Matt Busby and trinity statues on the outside you really get a sense of history.  Then you go inside and the place certainly has the wow factor when you look out across the pitch.  There were excellent facilities within the stands too. Away fans are housed high up in a corner behind one of the goals, and the atmosphere generated by the Spurs fans was great.  The United fans didn't particularly add to it though, the occasional chant of "United, United, United" was about all they could offer.  Great stadium.