Yes, big time. I am not experiencing this problem with any other games or streaming or whatnot.
About 60 to 120 seconds into the game, I get a hilariously massive ping spike (500-9000 according to the in-game ping thingie). While it's happening, everything except my champion freezes, I cannot see my cooldowns, spellcasts, or mana expenditure; also cannot see gold spent or item purchases appear in my inventory. These spikes continue until the end of the game, with random "attempting to reconnect" dispersed amongst them.
So far, literally every single game I tried, in every mode, etc. has resulted in these spikes. The game is practically unplayable. Interestingly enough, this doesn't actually prevent me from sending in commands - if I, for example, see an enemy champion moving into a specific spot and then try to walk into that spot and cast spells blindly (or give an auto attack order), my champion complies as if nothing is wrong. This seems to be entirely a problem on visual feedback from the game kind of spikes.
This has to be on Riot's end, I think - I am assuming that their servers are registering all my inputs, but I am not getting all of the data back. I tried checking my firewall settings, turned off antivirus, repaired the installation, restarted computer, nothing helped. The one exception, is that I can spectate games with zero problems. This is explicitly happening when I play.
If it matters, I live in NJ.
Any ideas on how to fix this? This is literally "might as well uninstall" level of gamebreaking.