I have always liked Cole Porter's music. This is certainly not a greatest hits collection by any means. The movie showcased a certain part of Porter's psyche, a less salubrious side, that is hinted at in the music albeit ambiguously. The way the songs were interpreted in the movie gave me a new and deeper understanding of their meaning.
Robbie Williams interpretation of De-Lovely, and the sheer brilliance of his voice is a highlight for me. He is the closest there is today to Sinatra, albeit more in a tenor range. I also particularly liked Sheryl Crow's emotionally stylised version of Begin The Beguine. Alanis is excellent, even though I am not a fan of her other work. Every Time we say Goodbye by Natalie Cole and Love For Sale were also very well done. Ashley Judd has an excellent voice, and I wish I had heard it more in the movie. Some of the other songs were not particularly memorable.
It seems to me that you either like modern versions or traditional interpretations of Cole Porter. Traditionalists should check out Sinatra sings the select Cole Porter. Modernists should check out Red Hot and Blue Cole Porter.