I think alot of the critisism comes from people used to fan led (ie not profit) small conventions, expecting a straight 1-1 scale up - which was ambitious to say the least.
Overall I went away as a satisfied customer, so this is me trying to nitpick:
Parties were a dissapointment (but I've been to alot worse), although I spoke with a couple of the organisors during the saturday night & they weren't happy with it, so am guessing they were let down by providers (also - drink prices were set by excel & are normal for big london events I am ashamed to say).
Free star talks - this was, to me, the biggest problem. If you weren't in line by 10am you couldn't get tickets for anything all day on Saturday.
In future, maybe say something like Gold pass gets 5 stage B talks, Silver 3, General 1 (per day) & as already said - alot more room needed (also stage C & stunt stage need sound proofing from other stages).
Debates & other free talks - given this was an official event, I would have thought some video clips to illustrate the talks would have been used.
Museum, Bridge & filmwerk shop - a clearer discussion needs to be had with the providers; museum was small, shop was expensive & the bridge was damaged by the end of the weekend.
Stunt show - I have got to imagine the organisors were let down here & they didn't really know in advance what they were getting supplied.
Fan clubs - suggest you approach them rather than hope they come to you next time. They will really put on a great display if you ask them to (look at what one guy did just on a whim at the custom house hotel).
and speaking of fans - ask for some to get involved!, a fan council might help smooth relationships.
Finally, a huge well done to the guys & girls on the ground - a fantastic job done in difficult circumstances.