I've only had these for a few weeks but so far am well pleased. They look great, feel comfortable and so far the lenses have no scratches at all, although I make sure I put them in the case, which by the way is also quite handy.
On the slight negative side, the lenses aren't dead quick to change round partly because the frame seems a bit delicate, although I reckon you'd get used to it. A reviewer on the Argos site said he snapped the frame whilst changing the lenses once, and another said they'd bought two sets to save changing them around, which isn't a bad idea considering the price.
The yellow lenses (lighter than the amber colour shown) make everything in daylight seem almost too bright yet falsely rose tinted, then you take them off and the world looks blue and depressing for a short while. Maybe I'm just not used to it but I think amber ones would be easier to get on with. I use the clear lenses. Haven't tried the yellow ones at night yet though.
The rubber nose piece is comfortable but is unadjustable. I reckon they might ride up the face of someone with a large nose, although I'm guessing.
These are just small negatives though. I'm amazed these glasses are so good yet so cheap.
Edit: The arms don't have much give in being bent the wrong way, and one of them snapped off after I whipped the glasses off my face whilst cycling. Be careful not to do the same!
Edit: I've now lost both rubber nose pieces and a rubber arm, and am having to use Sugru to replace them. I'd recommend taking these rubbber bits off and supergluing them back on before they have a chance to get loose.