Amy Winehouse has an incredibly distinctive and easy to lsiten to voice and she uses it well and wrote some powerful evocative music. What else are you looking for in a musician if that's not talent?
Now whether or not you consider popularity tantamount to talent is irrelevant, the fact that she wasn't pushed into the spotlight in America has no bearing to her quality either; she had 9 top 100 tracks in the UK, Back to Black was the best selling album here in '07, and the 3rd best selling of the last decade.
Saying she had no talent is absurd, you just have to listen to her voice to hear talent.
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I hate people sometimes.