I just "upgraded" from a MBP running SL to one with Mountain Lion about a month ago, and I'm about the throw the ***** thing on the floor. It is UNUSABLE. First off the scrolling goes from normal to SUPER FAST for no good reason, causing me to totally lose my place. This happens over and over and over, and there is no way to disable it! Then there's the ***** rubber-banding effect. It wouldn't be a big deal if it were just at the top and bottom of each page--but it's on the sides too! Which makes the entire page slip around when I'm trying to scroll and read text, and THAT is a ***** annoyance. Again, NO WAY TO DISABLE IT. Then the cursor is erratic...it'll suddenly start moving faster and then slower, causing me to have trouble clicking the right places because it's so unpredictable and imprecise. WTF. And if that all isn't bad enough, the 3-finger swipe gesture between webpages only works HALF the time. The other half it is completely unresponsive. I am incredibly pissed and regretful that I sold my MBP running SL (it worked FLAWLESSLY) and "upgraded" to this horrific mess. And from what I understand I cannot go back to SL on this new hardware. GREAT! How come I'm not reading others complaining about these issues????