I have experienced first hand bad interference on the mains line at a relatives flat, which caused a lot of problems with his PC.
That being said I was still a little skeptical of what improvements could be made here, AV experience is always quite subjective anyway and I am dubious of gushing reviews in What Hi-Fi for a £150 kettle lead.
I was looking for a nice solid mains gang adapter anyway and this mains conditioner is great value and I have to say I'm a sucker for exposed components with that toroidal transformer on show.
Now how does it perform? Well visually can't say I've noticed any difference however visually I've never had any problems anyway.
Audio however is noticeably improved, especially with my Sub Woofer, in quiet moments it would pick up an annoying interference type noise however this has cleared up!
All in all it's a nice solid gang adapter with a mains conditioner for a great price.
I plan to buy another one for my Home Cinema room, once I get round to building it ;-)