I've used several builds starting with 7000 and working up to 7068 as of yesterday. It (7068) is the best build yet by far imho. There are some nice tweaks and improvements and overall usability is much improved. They still have Games lumped in with Computer and Network on the start menu, but I'm sure that'll change as builds progress. They could also do with setting the user folders (eg Username, Documents, Music, Downloads) into alphabetical order too; Downloads currently appears at the bottom of the list which doesn't feel or look right.
About the only 'actual' problem (the above are purely cosmetic) I find still apparent is that I can log IN to my FTP from Explorer, and then download files, but it won't let me upload any. I just get an error about not being able to log in to the server. I did submit feedback on this in build 7000 (when FTP wouldn't log in at all) but I can't do that now.
"Oh, hai! I'm running leaked build 7068 and I founds bugz!!1!"
Overall though it's a brilliant OS and way better than Vista (or, what Vista should have been

). I have it on most of our PCs and laptops now, as well as my family's lol Interestingly, my sister's Fujitsu laptop (1.7Ghz Celeron M, 1GB DDR2 RAM) struggled to run Vista Basic. Win7 7068 Ultimate flies along on it even with Aero enabled.