There is some useful information here:
http://en.wikipedia.org/wiki/COM%2B
One thing they say, is the COM architecture has become outdated by Microsoft's .NET framework. That's one reason people probably don't use COM+ with
COM architecture, when they could just use C# with
.NET Framework.
Skim through some example code. See if Com+ is pleasing to read and write. That aspect seems to have a big impact on a language's popularity as well. *cough*Pearl*cough*.
One thing to remember is don't learn a language because someone else is learning it. Who knows, maybe you might need this language in the future. Am I the one to know? If you're not restricted by a career or another hobby, why not sit back and cook up a couple things in COM+. =P