DO use Comments rather than notes (unless you need callout of Element Properties) and DO stereotype Comments strongly

PROS of using the Comment:

1. It is a reusable Element of the model and changes made to a Comment in one diagram will propagate to other diagams
2. It can (and should) be stereotyped strongly. If you are not using a strong stereotype please DO NOT display the <<comment>> stereotype, I suggest that in that case you simply do not show stereotypes.
3. A Comment can be packaged, and you can show the owner (try it).

CONS of the Comment:

1. You can't do Element Property callout into a Comment, for that you must use a Note.

Visit also:

• What is the difference between a Comment and a note ?