I agree with your assessments, but unfortunately these things take time. Having spent the money on my own license, I feel your pain.
The NURBS kernel has indeed been improved since SI3D, but the tools that use the kernel haven't really been built yet which is why it appears to suck. When the tools come online (whenever that is), I think you'll find a much improved NURBS toolset.
The particle engine may not have been improved from the user's perspective, but at least you can now render your particles with the rest of your scene and have a few other niceties such as collision scripts, tangency control, and true raytraced shadows. However, particles do need a heavy cleanup.
Agreed on all fronts, much improvement still needed in a few key areas - but that's not to say that XSI isn't useful.
The one thing that really gets my goat right now is that you can't run mental ray in standalone mode anymore. I like to develop shaders in my spare time for fun as well as for solving roadblocks I run into while using XSI in production for clients. Running mental ray in command line mode is needed for efficient debugging of shaders. Also, there are a bunch of features in mental ray that XSI doesn't yet support (like contour shaders or cylindrical area lights), if I want to work with these aspects of mental ray, I have to hack .mi files and integrate them myself AND purchase an additional mental ray license so I can check my work. After paying for XSI Advanced, you'd think this would be part of the package, but it's not.
Matt
Matt Lind
Animator / Technical Director
Softimage certified instructor:
Softimage|3D
Softimage|XSI
speye_21@hotmail.com