Malware is a broader term than spyware, don't be fooled into thinking
they are equivalent. There is much that this program won't detect, but
it should be pretty good at what it is designed to do. Funny that MS
practically created the market for programs like these.
Check it's installed how you want it. It likes to run a daily scan and a
permanent in-memory scanner. I'm pretty sure I told it not to during the
installation.
Set it to warn or quarantine only, not to delete: there have been
several instances of false positives.