Coming from the UK, the city trash and cycling standards seem fine :) There is a darned hill in the way of everything in Brussels, but I brought my bike helmet and buzzed around on hire scooters.
I agree with another poster here, the ventilation in some rooms will just be intolerable for some people. Sometimes windows are opened and you can sit near them, sometimes not. Quite often you will have walked across campus and squeezed onto the floor at the back of a busy room to sweat, straining to hear someone mumble.
The atmosphere around the grubby 60s uni & grey weather is non-existent. But the live streaming is apparently excellent. You don't need to travel to see the talks, and it's easier to quit out of a bad one :)
It's a logistical marvel in some ways, but also a total white boys club, the most homogeneous conference I've ever been to.