I would be really interested in this. I don't think it is even under the best 500 american films of the last ten years, but maybe your argumentation will bring me to appreciate it more. Jonathan Rosenbaum has it in his 1000 best films of all times list (so he may be in agreement with you), but I sadly didn't find any writing on it.
I myself thought before Sunset a far better film, one of the best of last year.