I skype almost on a daily basis and introduced it to others (PC and Mac Users) who are pleased to have it for long distance calls out of Switzerland.
Giaguara : I think the options are enough if the result you want to obtain is do one use Skype or not.
Otherwise you'd have to add : frequency of use/ type of calls (short-Long distance) other features used like Skype out/in etc... but that sounds more like a poll skype should make to its users, rite ?