Most people, based on posts on several forums, seem to be experiencing significantly shorter immigration lines at the new BKK. I've had two international arrivals to date. For one there was no wait, for the other my wait was 120 seconds. From stepping off the plane onto the jetway to stepping into a cab I'm averaging 10 minutes, this includes a stop for a duty-free purchase, and no checked bags. Taxi time is also a bit better for me, ~ 25 minutes vs. 30 minutes, even though the new airport is 3 kM farther. The shorter travel time is due in part to easier access to my street coming from the new aiport.