I tend to agree with VictorianSqualor. Imho, Amy Winehouse is hugely talented and I love her songs (not so keen on her lyrics so I don't sing along as I otherwise might, or play it when dd is around). BTW, one cover does not negate the fact that the majority of her output is self-penned.
People talk about boycotts which is just silly. As with any other product or service, if you don't like it, don't buy it but if you do, then do buy it. If she puts out quality merchandise and it is successful, while the bad stuff (e.g. bad performance while chemically altered) bombs, she should get the message.
Whether she can use that to motivate herself to sort out her life and her addictions is up to her and by no means certain but a boycott is hardly going to do the trick, is it?
Now Amy McDonald I also like though she needs to button her lip, imho. She has publicly slagged off a couple of "reality" type talent show winners in recent months. A lot of people might have some sympathy with her views but for an artist to express them in public is hardly the way to win friends in the industry, is it?
The one I don't "get" is Katy Melua. Hearing her, for me, is like fingernails down a blackboard. Yech!