hah, literally the only reason I used it. After Safari started freaking out with HTML5 videos I dropped it for Chrome. I was going to try it again but not anymore. I dont think Safari has a lot of life in it, they will see a further drop in market share now.
I hope you're not talking about the issues the beta had. It would be funny if people were judging software by unfinished versions again. If so, you should give Safari another chance. It's still faster than Chrome and all the HTML5 issues I had in earlier DPs were fixed with DP4 and it's subsequent updates. Nothing seems to be new UI/features wise in the GM thus far so it's likely been all bug and stability fixes this time around. Even better.
In regards to Activity window being killed, thus not accurate either. It's no longer a separate window by default, but the same functionality and then some was put into the Develop menu under "Show Page Resources" which pulls up a particular section of the new Web Inspector which is vastly improved. It even has the exact same keyboard shortcut Activity had (command-option-A). From there you can have it pop out as a separate window if you prefer. The only thing it doesn't do that I can find is give the data size next to the asset downloaded.
Hope that entices you to try it again and forget your beta woes.