Compare with Singapore Changi (half the airport was still being built at the time it opened), Hong Kong International (cargo traffic was moved back to the old airport after months of chaos), Bangkok Suvarnabhumi (domestic traffic was moved back to the old airport after months of chaos), Paris Charles de Gaulle (the ceiling of the new Terminal 2E collapsed, killing four people, and the entire terminal is now being demolished and rebuilt), Denver International (opened 16 months late with a baggage handling system that never did work and was eventually scrapped) and even Tokyo Narita (riots killed several people, and opening was delayed due to sabotage).
The only surprising thing about the trouble at Terminal 5 is that it seems to be coming under control already, mere days after opening.