Mine seem to be unique, I haven't seen a similar comment, yet. iPhone 6, iOS 8.0.
Speed is fine for me when wifi works, and I can always see networks, and appear to connect to them. But after many hours, maybe 24-36hr, wifi is no longer functional. It appears connected, I can see networks, I can disconnect, pick a different network and appear to connect to it, etc. But zero throughput. Not slow, zero. Rebooting fixes it, no combination of playing with wifi/cell/airplane settings seems to do anything, I have not reset network settings since I don't want to lose all of it if I can avoid that.
I'm still on 8.0, I've been waiting on updates to avoid new problems. I guess for now I just should reboot once each morning.
My iPad Air has no wifi issues, also still on 8.0.