I realize this was asked by someone in EUW, but I live between 3 and 4 and half hours (depending if I'm at home or at university) from the servers in Chicago so my ping normally sits around 18-26 ms depending on which place I'm at and the time of day, and if anything else is running (Netflix causes spikes like crazy), and when I do experience ping spikes which happen from time to time, it completely wrecks my game play. I will notices my ability to dodge properly start to decrease in the the 40's and 50's and in the 100's it's hard for me to make sure my abilities land where and how I want them, and once I'm in the 200's+ I often sit under tower, and will try and farm, and hope I don't get dived because especially if I'm playing a squishy I won't be able to react fast enough to survive. So I think it's a huge deal, but at the same time it depends on who you're playing with/against. If everyone in your game is sitting at between 200-220ms for the most part it probably won't matter as much since you're all experiencing similar delays, but if most or all of your team/ the enemy team is pinging between 20-40, and you're pinging 220 then that's going to be a huge issue.