Not at all.
The COMAND unit is quite a fussy beast and can take a dislike to some CD's,
Usually commercially produced muisc CD's are OK, but home burnt ones can play up. Specially if you stick labels on.
My COMAND is fine providing I use good quality CD-R's. All I do is write on the disk with a CD pen. Never stick a label or anything else on the disk. And keep them clean.
Of course your unit may need a clean, specially if the car has at some point been used by a smoker. Smoking around any type of laser device does it no favours as it coats the lens with a microscopic film. In which case use a good quality CD lens cleaning disk.
Ejecting CD's is a common problem and seems to get worse on a hot sunny day or if the unit has been used for several hours.
A tip is to GENTLY tap the COMAND unit near to the cd slot just after you have pressed the eject button. Only use your fingertip and do it in quick repeats but GENTLY.