Robertson's Greek Grammar

On Fri, 22 Apr 1994, Carl Conrad wrote:

> A.T. Robertson is AWFULLY--I dare say AWESOMELY good on quite a number of
> issues; it is remarkable how a work produced so relatively long ago can still
> be so valuable (well, I guess that's not SO remarkable, but it is pleasantly
> surprising). One can come to learn a lot about the history of the Greek
> language from the large edition of his grammar.

I read somewhere several years ago (can't remember where!) that 
Robertson's grammar was obsolete and had been superseded by 
Blass-Debrunner.  I have both of them and have read all of Robertson's, 
but have only referred to Blass-Debrunner.  Any opinions out there?

Tina S. Lau
Technical Services Librarian
Cuesta College Library
San Luis Obispo, CA 93403-8106