I've heard a lot of negative stuff about web summit organisers. 'Inviting' people to have a stall at the summit, then asking them to pay. Then putting all small startups in a hall far away from everyone else.
There might be a lot of negative stuff around, but the industry is all there and it's a great place to meet people. At some point, if you work in the industry and you're not there, it's a big miss.