Some initial ideas (I'm sure there are many more):
A) A table name property, that returns the name of the table that the operation affected rows in.
B) A rows affected property. Yes, I can set up a connection and query @@ROWCOUNT, but why should I have to do what the API can do for me?
C) A property that returns a collection with all of the column names updated (and even better would be other metadata, e.g. data type, precision, length, etc)
... providing even just these three properties would shift CLR triggers quite a bit further into the realm of being useful.