Having flown to Changi for over the past 23 years, I really find nothing to complain about T1, T2 or T3.
Yes, I know it is a downgrade from T3 to T2 for UA flyers, but it is still a world class facilities. T2 has gone through upgrades to provide better experience for the passengers.
Some gripe about the walk in T2, I have to say the following is not much better:
1. LHR (as many have mentioned)
2. EWR (from one end of C to the other end)
3. IAH ( no need to explain about this maze)
4. IAD ( from one end of C to D)
5. ORD (from one end of C to the opposite of B)
6. HKG (up and down the escalators)
7. FRA (worst maze than IAH)
8. PEK (just massive and long Chinese immigration lines)
... and many more