Just wanted to add to the mouse delay that I was using a mouse at first (non microsoft) and it was really bad. Delay, jumpy, choppy, took a while to get the pointer on something. I broke down and got a magic trackpad and it went away, but it's still irritating that i have to buy stuff to fix problems that should not be there.
You got lucky. On the thread about the issue, people using the Magic Trackpad experience lag as well.
And, to the ones saying people like to come here and say bad stuff about the OS, no, that's not true. It's no coincidence that the average score on the App Store is really low.
I love my Macs and love OS X but Apple really messed up with Yosemite. My Macbook Pro can't handle simple graphic animations like Exposé, too many windows of a certain app open, has severe delay using a mouse made by Apple and can't handle large downloads because the Wifi is dropping every minute. Guess what, under Mavericks everything works like a charm. Yes, a i7 Retina MBP with 16GB of RAM is capable of handling all that :O It looks awesome, yes it does, and the features added, even though I don't own an iOS device are great but I think it's about time Apple decides that a 1 year cycle between OSes is too small. No wonder people loved Snow Leopard. It was based on Leopard, Apple added TONS of features that we still use nowadays, managed to improve the overall performance and still released 8 (EIGHT) point updates to fix issues. Right now, Yosemite still has serious issues and Apple is probably preparing to present/release the new OS X version that will be available this year. Then I have friends of mine with 2009/2010/2011 Macbooks and say that Yosemite works like a charm. That only shows the lack of optimisation there is.
There are too many complaints for it to be a mere coincidence or people just saying it's bad because they feel like it.