I have had Wifi issues on ALL of my devices since 6.0.1. 2 different iPhone 4S's, 2 iPhone 5's, and iPad 3... I thought it was my Apple Extreme router, so I went out and dropped another $200 to upgrade to the newest version. This did NOTHING. I've read to disable the encryption. This is not a good solution for me. I tried it to see if it would solve the issue. It did not.
I have full bars, and it is painfully slow on the 4S especially. I'm fustrated beyond belief. All these devices worked perfectly until the updates. This is 100% a software issue, and I thought 6.1 was going to solve this. Not at all. The funny thing, when I bring the device into the Apple store, it works like a CHAMP, but as soon I try to connect to ANY other wifi, my house, Starbucks, ANY public access point, the wifi is horrible. What is so magical about the Apple Store's wifi connection?