I don't know about brands to avoid but mine is a Russel Hobbes and it's great.
I think the slow cooker is best for winter foods but I like it in summer because if I feel like a curry but I don't want to slave away near a stove it's perfect. I have thing for curry in summer - I'm not sure why. It makes no sense to eat hot food in hot weather......
IMO there few things that go together as well a hot curry, a cold drink and a summer evening.

I soak chick peas, beans etc overnight (in the fridge) before cooking them and I also keep a few tins for the times that I don't have any pre-soaked.