I'm not going to write everything again, but the point I touch on is version issues and how hard it is to even try to package GNUstep.
Someone mention how hard it is to install GNUstep, which I find is already extremely easy. Anyone who has ever tried to install GTK will understand where I'm coming from. To install GTK, you need GDK, which in turn need GLIB, and all along the way you have 10+ dependencies for each one. GNUstep is already the easier framework to install from scratch, saying it's hard to install is really a baseless statement. I think the main thing that needs to be worked on is integration with the distributions. As was already point out, GNUstep's Debian packages are sorely dated. I try to keep updated Slackware packages under the FTP but it just now became a real burden with the insane work that is needed to match stable libraries, and in the end I still end up with outdated releases (stable is far behind trunk).
That whole version thing aside, I think GNUstep already has awesome Windows support, and should actually be put on hold. There are currently more than enough issues pending in the main platforms (the Unices) to think about supporting another platform (ie. cairo is still not 100% usable, and theming is still a must).
As for the slogan, I really don't think GNUstep should try to be the "poor man's Mac". Mac really isn't that great (talking about the Mac itself, not Cocoa), and not a lot of people use it. In my opinion, GNUstep should try to put a gap between it and Mac while emphasizing the Cocoa/OpenStep similarities and ease of use. Something like "GNUstep - code less" (a pun to the "code differently" idea); "GNUstep - write once deploy everywhere" (this one was proposed over a year ago by someone else as a pun to Java's "write once run everywhere"). I, personally, like the "write once deploy everywhere" one... maybe a hybrid: "code less, deploy everywhere".
I understand most of these criticisms have already been mentioned to death and most are tired of hearing it. Sorry... I just had to get it out.