This is not really an alternative to the Epson P2000, because the P2000 comes with a large (3.8", if I recall correctly) and bright display where you can preview the RAW thumbnails, JPEGs, videos and listen to music, while the Compactdrive is only storage.
If what you're after is only the portable storage, then there are several alternatives to the P2000 (40 GB) or P4000 (80 GB) out there, several of them which are probably very useful.
I have no direct experience with this particular product, so I'm not making any claims regarding how well suited it is to its task.