It is not only the better features, the better forum, the better artwork, the better concept - unity of course is a very stable engine. And the community is very active. I miss this frequency in the gs forum since years. Yes, I payed 300bugs for the A8 update - but I buy the unity3 pro for sure the next few weeks. And you can definetly say - the community of unity is more developer oriented in compare with the gs members.