You shouldn't experience any lack of power and changes in driveability. Keep in mind that models for the US market usually have a 'Service engine soon light instead.
If there are no other symptoms, you can safely use your BMW until you have a chance to fix the problem.
Half Check Engine Light
Half Yellow 1/2 'check engine light indicates an engine problem that will affect the engine's performance. It comes with 'Engine fault! Reduced power' message on your iDrive display.
This can be caused by the failure of various sensors or solenoids.
The engine ECU will cut down the power output to protect the engine. You might also experience some driving difficulties. Even so, your BMW will still get you home. Drive slowly and don't push the engine. Avoid unnecessary driving until you have fixed the problem.
Red Check Engine Light
The Red 'check engine light indicated a serious issue. It means that something is seriously wrong with your engine.
Stop the car as soon as it is safe to do so. Please turn off the engine, let it cool down, and inspect it for unusual sounds and leaks.
Monitor the engine temperature. Don't allow the engine to overheat. Do not drive the car if the engine overheats. This can easily destroy the engine.
Use the YOUCANIC scanner to find out why your BMW check engine light is on.