IMHO their cilent on the tablets is pretty good, it's easier to use than most Maemo apps and it's worked fine for me in the year or so it's been out. Even though there were compatibility problems with the N810 mentioned above, the OS2008 version of Skype has even better sound quality than the previous version.

It has started dropping calls more often lately, but I suspect that's something to do with the networks used by Skype rather than the app itself.