The new codex contains several very good units, like Grey Hunters, Long Fangs, Wolf Guard.
The basic problem is synergy.
All parts of the army should play together in some sense.
Currently, I see two good lists.
First, an army that is reactively played which brings the enemy forward, slows down his advance, and then wents for his throat.
An army like this would include
GH's and
LF's.
Second, a mech army that fields Rhinos filled with
GH's and
BC's supported by Thunderwolves, Fenresian Wolves, and Land Raiders filled with Wolf Guard.