Not really. The WC 51 is a decent enough unit. If you put inside some riflemen in it then it has pretty good DPS. Put a lieut or a captain inside it and it performs pretty good.
The M3 halftrack is total crap, though. If it was like the M5 or the 251 then mechanized would finally become a good doc.
I actually like the M3 halftrack better. For SNGs I spent an entire day just playing with Mechanized in 1v1. The Nerfs to the WC51s health and mobility made it like a more fragile and less useful Kubelwagen. Its also to slow to be a decent transport unless it goes in a straight line. Its much like the SU85 at a different scale. Its very cumbersome now for a light vehicle and its very fragile. Even the Benefit from putting squads inside dont make up for its short comings. I would take an M3 scout car over it ANYDAY OF THE WEEK. Its pretty damn bad for what it costs.
The M3HT is actually quite mobile and can garrison two squads. Funny to put the Captain in it with another Zook squad and counter Pumas.....
The WC51 is just to slow for these Hijinks. And what I mean by slow is its use in practice not its top speed. In practice you need to slow down and turn around etc etc. Its bad at these things. Definatley not worth the Price of a Rifle Squad plus fuel.
Edit:
With its current Performance it should cost the same as a Kubel IMHO. Its a 10 fuel unit AT BEST.