Highly reccomended !
I use Relakks since over 4 years and can only praise them !
My experience shows that the service is reliable, provides a good speed (can even Skype through Relakks).
I once had trouble with a payment (I messed up) but they where very responsive and helpful (responded/solved problem in less than 12 hours).
Apple Mac friendly, no need to install additional software as they use Mac OSX built-in PPTP client !