I had downloaded the beta earlier this month. Anyways, its pretty fast compared to the old IE but still not as snappy as chrome or opera. It really shines when there are a lot of graphics on the page due to its usage of gpu.
Its still buggy for me, sometimes uses 100% cpu for no reason. I am going to stay with opera, its small, fast and you are not worried about somebody snooping on your information like chrome. I have never been a FF fan although it renders most of the stuff correctly which other browsers don't.
