I have been using it. It is real fast. In fact Mozilla and IE are no match when it comes to the speed. However there are some observations against Safari.
1. You can't use ctrl+enter in the address bar to and rather have to type the full domain name/URL.
2. The chat window doesn't work for gmail.
3. It is believed that it is not as secure as IE or Mozilla.
4. It is believed that it crashes once in 3 hours on an average, howver i haven't experienced such problems yet.
5. I was not able to host an image in imageshack as it gets stuck when we try to upload it.
However this being the beta version, we can expect a neat and a fast browser at the end of day. But i still believe that apple have hurried launching this browser.