I heard a lot of complaints while I was at the TESOL Convention. Here were some of them:
It was disorganized.
The maps and signs were inadequate or unclear.
Volunteers were not well-informed, and sent people on wild goose chases.
In general, a shorter convention meant more schedule conflicts than usual, so people were double-booked and could not attend everything they needed to.
Popular speakers were scheduled in small rooms, so people had to wait a long time to get into sessions and then were sometimes turned away. The rooms on the fifth floor of the Sheraton were infamous. They were so overcrowded at one point that fire marshals or police were called in for crowd control, and there were humongous lines at the elevators. People were allowed up only when other people left. This was not a problem in the EV; events were well-attended but not over-crowded. Mini-workshops filled up but if you got there on the first day you could sign up for anything, and if you came to full sessions you could often get in if people who had signed up didn't show, or you could attend as an observer.
Inadequate and expensive internet access. In the hotels, free Wi-Fi was available only in the lobbies, and presenters were required to pay exorbitant fees for computers and internet access in their rooms (I was told over $800 per session!!!!), so many presenters opted to show only screen shots while others just resorted to presenting in the EV, which had constant internet access but very limited space.
Well, New York is an expensive city. The convention hotels were expensive, the restaurants were expensive, the convention itself was expensive for those who paid out of pocket. Everything cost more than it would in most smaller cities.