Uncomplicated, Inobtrusive, but very Effective.
I've used Bitdefender for years now and can honestly say that I forget I even have it running. The only effect on my computer it has is to keep it virus free. No slow down, as with other anti-virus programs. It does its own thing without stopping me doing mine. It also gives me a short cut to general maintenance like defragging and decluttering which helps me to remember to do it! A great program.