The nice thing is that you can have it and the production version of Safari running at the same time. It preserves all of your settings and bookmarks too. I've only experienced a single problem with it lately, and it's related to my installation of Inquistor. This morning, ironically while I was composing this post about how stable the Safari beta is, the browser shut down with an error message indicating that I had extensions installed and that it could cause unexpected shutdowns. Oh well.
It does appear a bit faster than the current production release of Safari.