Had them for about 10 years, never had any problem with them, but definitely worth paying the money for good quality. I use Vision Express. Not sure when they will be open to do a proper eye test.
I got varifocals for the first time about two years ago. I cannot recommend them too highly.
I have been short sighted since I was about fourteen but, in recent years, my ability to read close to particularly in poor lighting conditions has been severely compromised. I could do it by taking my specs off, but that's a bit of a pain in the arse. Varifocals were a revelation almost as good as when I got my first ever pair of specs and found that the World wasn't fuzzy in the distance.
I will endorse NS's point about good quality. Basically, the more expensive the lens, the more of it is usable. Varifocal lenses have an area at the top which is your distance viewing prescription and an area at the bottom which are reading lenses. You can't see clearly out of the bits in between where the one lens merges into the other. In particular, on cheap lenses, the bits on either side of the fairly small reading lens part are completely wasted. This
diagram shows what I mean more or less, except it's more charitable about the unusable areas than I would be. Anything in it labelled "soft focus" or "intermediate vision" I would describe as "blurry".