rare breeds are cute, but rare for a reason.
But not necessarily a very valid one - sometimes it's just fashion and again, it depends what you want. Being rare doesn't mean that there are any specific difficulties with the sheep.
We keep Coloured Ryelands. We've gone with them because we wanted a British traditional breed (the breed was classified as rare but is now a minority breed) to produce quality lamb for ourselves. The breed produces a good carcase and the lamb is beautiful (we lamb in April and the tup lambs are away at the end of October off grass) - we sell any surplus as half lambs. The carcase is fattier than the commercial breeds but very tender and flavourful.
The fleece is good quality - we sell ours to spinners and crafters, but it doesn't cover the cost of shearing. It also has a big fleece, so you do have to be careful of fly strike.
We'll be lambing for the fifth time in 2013. I haven't found them to be the most prolific breed - about 150% lambing, but my ewes have all been good, attentive, milky mums. Can't say they've always lambed on their own - we had a C section this year but that's as much down to management as the breed and I've had to lamb one every year. Never had to bottle feed any except two that we topped up this year because I felt the gimmer didn't have a lot of milk.
The Ryeland isn't very big, is very docile and friendly. If it gets out, it will go as far as the next clump of grass. If you haven't seen them, they look a bit like Ewoks