What is the outlet temperature of the air in the ducts? The only way to tell if things are working properly are to check the operating pressures, temperatures, and air flow. If you didn't have a manual-J heat loss analysis done, the size may not be proper. This one is 25% less powerfull, and that may be the difference. The bigger question is how is overall comfort? If the air ends up drier because it runs longer cycles, you may end up more comfortable that a bigger unit that turns on and off. Continuous running removes more moisture, and that is often a big issue. If the air is drier, you can often feel the same at a higher temperature. the last thing, did they change the thermostat as well? The readouts on some never were calibrated really well.
At night, when it cools done some, can it ever get to the set point? If not, something is wrong.