I use it and am more than happy with it, some argue if you are careful you need nothing but accidents do happen.
Generally it seems to do pretty well in reviews and for most users it should be more than adequate, I have fixed a lot of computers where people that have been hit by trojans and Viruses and have to say in pretty much all the cases they were asking for trouble visiting some very dodgy sites and downloading stuff they shouldn't have been.
Here are a some reviews of security essential:-
http://www.expertreviews.co.uk/softw...essentials-1-0
http://www.techradar.com/reviews/pc-...-640587/review
http://www.pcadvisor.co.uk/reviews/i...eviewId=117961
Something worth considering if you decide to go down the comercial route is to keep an eye on reviews as what can be the best one year is not necessarily good the following year.