We like the ease of use and the administration of the portal - its also very effective.
Hands down the best software on the market, made by some of the brightest in the industry.
Security services offered, product features, service, ease of use. The signatures feature is also pretty amazing.
They have since been fully taken over by HornetSecurity and I regret to say that since that happened the response times for support requests has gone downhill badly.
I do not have much to report in terms of cons for the hornet spam filter.