I've used Exposure since they released it. It, generally, does a good and accurate job of mimicking most film types and grain structure. I use to shoot a lot of K64. I can't say it "looks just like Kodachrome", but it does a failry credible job. Actually, Exposure is the first software to do a truly good job simulating cross-process. It's worth putting in your Photoshop "toolkit" for later use, even if you find the Kodachrome not to your liking.
Nemo