I had no hardware problems at all, either on the Classic or the SS5. Granted, this is fairly recent, standard Sun kit but at least many Sun users can be assured that S/Linux will work today on their machines.
Many administrators prefer to install a large amount of public domain and open source utilities on commercial Unices. This often includes packages that have become defacto standards on the Internet, such as Gzip.
With Linux, almost all of this is unnecessary. You may have to locate updates if you're zealous about using the latest releases, but the supplied versions should be welcomed by most people. This is a particular boon if you're taking your SPARC home. I mentioned the large amount of public domain software installed on our office servers. The hours that have been invested in creating these binaries must be considerable. Linux spares you much of that `configure; make install' drudgery.
The Linux developers appear to have been less dogmatic about making major changes to common Unix utilities, such as forcing them to behave more consistently, easing their configuration or removing idiocies. For example, the man command acts much more sensibly under Linux than Solaris; it has a /etc/man.config file that specifies where to find man pages and what commands to use in interpreting them; it can read a man page file directly (even if compressed); it compresses pre-formatted versions; MANPATH can act as an addendum to the default paths rather than a replacement. A further example: the three variants of grep are derived from a single binary. Final proof: using tcsh and bash automatically instead of the original shells with all their limitations.
After putting up with the same set of historical irritations in every version of Unix for years, it comes as a massive relief to find someone prepared to tackle them whilst remaining mostly compatible with existing `standards'. (Essay question: imagine you were designing a new version of Unix from scratch and did not have to remain compatible with previous versions. What would you keep and what would you happily leave out? How much resemblance does Linux bear to your finished product?)