Microsoft admits Security Essentials offers bare-bones protection by design
The company has exerted little effort in advising vulnerable users to look to third-party offerings for greater protection
A Microsoft official has gone on record stating that the company's free Security Essentials software, by design, offers mere "baseline" protection for Windows PCs and users should turn to third-party offerings for more comprehensive security...
I never had any issues with MSSE (except a minor issue with uTorrent a while ago). I really like the "baseline" bloat and no-nonsense of it compared to, for example, the god-awful NOD32 we use at work :p