They dont last long, but they are soooo cheap.
The first time I bought a bra from Primark I expected it to be just average but I was pleasantly surprised. They're inexpensive (generally ranging between £2 and £6) and quite comfortable.
You do need to try them on in store as some come up a bit big but they don't stray too far from being true to size.
They're padded but not too much, just enough to give support and a little size boost and stop poking nipples showing through. The straps are also a good length and not too tight.
The range of designs is very varied in style, details and colours so there's something for everyone, and the majority can be bought with matching knickers which are very cheap too.
Since buying my first bra from Primark I've bought 4 more and I would say the same for all of them. They're better than the bras from competitor stores like H&M and New Look and in general a good bargain.