So far, okay.
We've used Symantec for mail filtering for 6+ years. Only 2 issues, that were in the last year this being the second. That said, they are still blocking malware and spam (as well as all our custom rules) and I was able to get ahold of support this morning. So long as this doesn't become a trend, I'm still happy with the service.
The constant notices/status has been good too.