Overall SIN is a large and well laid-out airport. Immigration counters are well staffed and there was no line either on arrival or departure. The customs officials handling GST refunds were polite and helpful. Security is handled at the gate much like Bangkok or Frankfurt so queues again aren't an issue. Plenty of shopping and restaurants are also available and the MRT station underneath the main terminal is a big plus. On the downside ATMs are awfully hard to come by - I could only find one working ATM in the arrivals area near the entrance to the MRT station and there are no signs indicating where it is. Also while security provided at the gate helps eliminate security lines it also means the seating areas don't open until an hour before departure and seating space is inadequate if you get there early and don't have lounge access.