They started doing a con in Cardiff about four years ago, they put one on every 6 months. I went to the first couple because they had excellent guests - Lance Henriksen, Robert Englund, Christopher Judge, Brian Blessed, John Rhys-Davies, The Hoff, among others.
Now I don't know if the guests made like, no money or something but since those first two the guests have been awful. A few extras and extremely minor characters from GoT and Harry Potter mostly. I think even if there were some decent actors I'm over paying 20-40 quid to queue for an hour just to get an autograph, I was just dazzled by meeting famous people the first time round.
As for the stands and stuff, I think Jinx said it best in that it's just looking at lots of cool stuff you can't afford, and even then it gets dull after about 20 minutes. Guess it's just not my thing.