Cloud door access control systems, Is it good me??

The answer is, "it depends."

Buying (or subscribing to) a managed service likely has a lower initial cost, but can be more expensive in the long run.

You need to shop for this just like any other managed service. What's the initial cost? What's the ongoing cost? How does the cost compare to doing it all in house? Are there competitors? What's the customer satisfaction of the service?

From a functional, rather than a cost, perspective, my biggest concern would be, "what happens if I lose connection to the cloud?" Is it fail closed (all doors locked) or fail open (all doors unlocked)? What is the risk associated with each scenario?