I can deny it. It was OK, but not amazing. I had to make pretty frequent repair calls on their gear--much more frequently than the less-technologically-amazing-but-solid-as-a-rock Dell and Compaq gear. IBM, Digital, and HP (yes, that HP, before they lost the Way) also had very good UNIX gear, but Sun had the mindshare during the '90s.
In terms of performance, even Linux 0.x on a 33Mhz 486-class processor could outperform a uniprocessor Sun/SPARC box at a fraction of the price.
I also question the sanity of anyone who thinks Sun's choice of 13W3 for a video connector was a good one. :-)
I don't know, the clustering on Solaris was pretty amazing, if we are just judging "ahead of time"
DEC's VAX/VMS had decent clustering in the early 80's.
Any Unix "clustering" system I've used (Veritas on Sun, HA/CMP on AIX) always seemed bolted on.
I'd say the basic idea of 13W3 connector was fine, what was not was not trying to agree with others on pinout, and evolving the connector in a way that made invisible incompatible difference whether you had DDC-capable or not