I flew both the A320-series as the 737-800.
My first impression of the 737 NG was a big disillusion. This was not the kind of aircraft that I expected from Boeing to compete with the A320.
Yes, it had new engines and wings, yes it had some nice LCD-screens. But that's it. Almost nothing has changed to the '60's technology.
After flying with it I discovered that the cockpit was extreme noisy due to the lack of isolation. Pilots at our company were flying with ANR headsets !!
The approach speeds are higher : it's a Cat. D aircraft (even the Airbus A330 is a Cat. C). Strange for such a small aircraft.
And then the AD's came; No speedbrake above 300 knots,... !!
Also due to the fact that the wings are thinner, we had several cases of de-icing the wingsurface at 10°C OAT after a long flight and with eco-fuel in the tanks. Never saw this in my life and I must say that it is very difficult to understand !!
When you come from the 737EFIS, the 737NG is a great aircraft but when you come from another modern aircraft, the 737NG is a dissapointment. But unsafe ??? It's on the limit I think....