SL1DER  Well, it launches. It finds and loads torrent files. It finds the tracker. Get's peer and seed info. But then the trouble starts. Although it finds the peers and seeds, and at times connects to a few, no data goes in or out. Port is open. Even tried letting it map the port. Both ways I get a green light and functioning connection, but no data transfer. I have never seen it connect to more than 4 peers at a time and zero data transfer. I even let it sit there all night and same situation. It also does not retain preferences across relaunches. The minute you quit, all preferences are reset to stock. After using this on Wintels, I was very excited to see it in action on a Mac. Very disappointing so far. I hope they get the bugs worked out.  
(Version 0.9b)

SL1DER  EGINZBURG, you should head over to the Transmission forums. Not enough detail about your setup here to diagnose, but you will definitely find an answer there. Could be, double router (Modem that is really also a router, Vonage, or wireless if you are using Airport). Check out the forums and your ports will be open in no time.  
(Version 1.22)

SL1DER  I too have looked into the differences between Azureus and Transmission. Transmission is hands down the better written and implemented application, not to mention better looking. However, the discrepancies that users see in download times SEEMS to be directly related to early releases of Transmission and it's supposed "compliance issues." Those issues led to many sites banning Transmission for use. As a result, although Transmission does a better job more elegantly for the peers it can connect to, it connects to far less peers as a result of being banned. If this situation has changed appreciably. please post and let us know. I can find no other reasonable argument for the differences in overall download times/speeds that haven't already been debunked somewhere by someone.  
(Version 1.03)