It isn't necessarily the "best" feral tank weapon, but it is a good weapon. Some of the other options may not be attainable because of raid access, though. Check out
Emmerald's lists for options.
I recently upgraded from Braxxis' Staff of Slumber to Earthwarden and really like the upgrade. Earthwarden has over 400 more dps than Braxxis', which is a really nice boost to aggro generation and for solo play.
But, really the answer to the question is: it depends. How are you approaching the Xpac? Getting from honored to exalted with CE takes some work. Is that how you want to spend the time before Xpac? Earthwarden will definitely help with leveling when the Xpac is released. So, it won't be time wasted necessarily. It just kind of depends on how think you want to spend your time before Xpac.