“These changes made new aircraft’s landing and take off and flight characteristics different from that of the 737.”
You say ‘different’, not ‘worse’. Is the plane, in the hands of a properly trained pilot, less safe than other airliners?
Yes. Even outside of any emergency, the plane is unstable due to the positioning of the new bypass turbofan engines, which the plane was not designed for, far enough forward from the wings to clear the ground. Boeing installed a flight control system they called the Maneuvering Characteristics Augmentation System (MCAS) to compensate for the aircraft center of lift being too far outside the forward and aft center of gravity range at certain power settings and aircraft attitudes.
Specialized aircraft such as the F-16 and F-117 were knowingly designed to be unstable without the computer controlling the aircraft (in order to gain maneuverability, compensate for the stealth design in the F-117 case, and to allow for variances of center of gravity depending on what weapons were loaded on the rails in the case of the F-16), but civilian aircraft are normally required to be stable in all normal flight profiles. One example of such stability is where an Air Canada crew ran out of fuel at 41,000 feet in a Boeing 767 and still landed the plane on a runway. The plane was nicknamed 'The Gimli Glider' because the crew landed it at Gimli Air Force base.
https://simpleflying.com/gimli-glider/
Yes. In a pinch, the 737-Max can be a tricky aircraft to fly due to nasty surprises in its flight control system. The two 737-Max crashes in Africa involved highly capable, well-regarded pilots who were not at fault.