[M3devel] Downsides of Modula-3 ?

[penn43 at gmx.com]

An object appraisal must take into account the problems too. So I am asking you, could you please mention any downsides of using Modula-3, in your experience?

Of course, the non-existent language community has already been mentioned as a major downside. 
And the lack of documentation.
What about other issues, such as compiler efficiency? Or interaction with foreign libraries?

Thanks

Marresh