Lack of functionality. Web interface is geared towards idiots who like approximations of data.
As far as a management portal, Sophos seems to play the ignorant. Tamper Protection management, detailed reports and the pandering display of "this computer hasn't updated in 3 days, 4 months etc. I'm human and I'm in IT, I can understand dates on a calendar. WHy is it that I have to download a CSV (when available) to get dates versus an annoucement of "about 3 months ago". Are you selling this to the enterprise or the end users?