Claw is a little better than it used to be if you use
Glyph of Claw. That, coupled with the fact that rake actually does good damage now, makes feral leveling much easier than in the past.
You can also throw on
Glyph of Maul for those times when you have to switch to bear because you pulled an extra mob or two on accident. It'll help with any lower level tanking you might do as well.
Me and a guildy are leveling some toons together. I'm running a rogue in full heirloom gear (emblem sword, Wintergrasp sword, 2x haste trinkets, shoulders and chest) who's sitting at 38 just absolutely wtfpwning everything in sight. She's a few levels behind me due to playtime, but hasn't had any issues ripping through quests as long as they are green-orange.
After you get kitty form, things pick up the pace, after mangle (everlasting ******) it's gametime. You can decimate anything that comes your way.
<3 mah drood :P