Short review
Was fun and felt like an up-scaled Eastercon.
Long review
Single complaint: the 1 hour 45 minute registration queue. This I'm told was caused by the lack of power sockets for the computers. This was offset by the incredibly prevalent wifi that I had to accept the T&Cs to just once in the whole 5 days. This folks is a modern public facility. Not like our shitty airports.
The Excel had one other 'problem'; their security staff would clear standing attendees from panels where seating had run out. I was cleared out myself from the post-apocalypse survival panel. I've been to many cons where I've stood or sat on the floor. But I understand the safety/insurance concerns.
Otherwise I loved the location. Vic and I commuted in and out and some evenings got back in 45 minutes. The Wifi meant I was in contact with mates all weekend. The eateries were mixed, but so plentiful there was never a long queue and loads of available seating. The dealers room and fan village worked great and I enjoyed both. Also loads of toilets; important!
I was kept very busy. I volunteered a couple of times on the
ZZ9 table and hung out in the con bar and village with friends. Went to lots of panels. There were a lot of diversity/LGBT panels and I'm really proud of British fandom for that. Since we were commuting I sadly missed most of the evening events but on the last night got to stay for the dead dog party in a hotel room which wasn't being used by generous friends. Vic and I also saw 'The Anubis Gates' stage production; all a bit mental. We also watched the Hugo awards which were neat.
Bloody well done to all involved. I remember how the Eastercon in 2008 was a massive success and boosted fandom's turnout. I think Loncon3 will be a big boost felt by our community for years to come.
PS I also bought/scrounged my own bodyweight in books.