Believe me there's much worse than SGN…
But, I was there 3 weeks ago and indeed, I found the ops pretty inefficient. Inbound was OK for immigration (in the afternoon), but outbound was another story. Despite a relatively early time on a sunday morning (7 am), the terminal was very busy and lines at immigration and security were very long and extremely slow. And no SkyPriority for immigration and security; which is a shame for a Skyteam hub (VN). And, yes, the staff is pretty rude.