Temperature calibration for MCP9808
And my question to you is if you think this is enough for a normal
  temperature sensing application


This is what the spec says on the front page: -

Accuracy:


±0.25 (typical) from -40°C to +125°C
±0.5°C (maximum) from -20°C to 100°C
±1°C (maximum) from -40°C to +125°C


My personal opinion on whether this is accurate enough is immaterial.

My advice is ask yourself if this is acceptable for your application.