I upgraded to the latest skype version 5.7 on my mac today and don't like it at all. Is there any way to go back to the previous version without losing my contacts and history?
I second that dislike (especially for the autostarting "Skype Home" that just gives me a feeling of annoyance each time I start Skype, not very good marketing).
And yes, you can remove Skype and install it again without losing any contacts. The 2.8 version from http://mac.oldapps.com/skype.php seems to work nicely. Your contacts are stored online in Skype's database. Just download and replace the new with the old version. You might have to really remove the "new" version first, and empty the recucly bin, then you can drag the 2.8-version to the Applications folder.
Since the 90s and the beginning of internet people have known that autostarting ads, popups, background music etc is at best tolerated and often hated. I'm sad to see Skype coming to this. If the Skype home was an Option I would accept it, but now when it's forced I'm sorry - Skype marketing team you did a mistake there.