They are okay-ish for a bit of occasional cover, but you can get full covers of same or marginally better quality for about £5-6
I bought one for an ex housemate who kept her bike in the garden chained to the clothesline pole (!!!) as her logic was "if it's in the shed or cellar I'll not be bothered to get it out"
Should have known that would also translate to being bothered to cover it up or not...but if you imagine a "mini skirt for bikes" that's about the size of it - shows off an almost obscene amount of wheel rim!