Read the following review at PC Magazine's web site:
http://www.pcmag.com/article2/0,1895,1926597,00.asp
WD does not even appear to be an improvement over MSAS.
A passage important enough to quote in full should give
you an idea about the level of protection you are getting:
"We ran WD through the same testing regimen that we applied to its
predecessor,
and found no real improvement in performance. Of the six commercial
keyloggers
we use for testing, both MSAS and WD detected just one, and they only
partially
disabled it. Where MSAS didn't block any of the keyloggers from
installing, WD
tried and failed to block one. WD did improve slightly over MSAS in
blocking
spyware, detecting two programs that MSAS missed and fully blocking one of
them. But with spyware already on the computer, WD actually removed fewer
threats than MSAS had. We found this surprising and double-checked the
earlier
results, and found that in three particular cases WD left behind
significant
executable file elements that MSAS had removed successfully. Overall, WD
removed six spyware threats, detected eight without fully removing them,
and
completely missed one."
Cheers!