I dont really follow Dota competetive scene, but I went to ESL Katowice with some friends (Im from Poland), it was quite interesting. One thing that was pretty surprising was how little people were actually there, granted the venue was huge, but it was mb 1/3 or even 1/4 full on Saturday evening. Also, it kinda sucked that you couldnt buy alcohol anywhere, I cant imagine that the Dota main audience is a lot of kids.
Other than that, pretty fun experience, though me and my friends were drinking hard, so I dont really remember much abot the actual games