In some respect, yes the Solaris system has fallen behind the likes of Linux and *BSD. Particularly in the availability of third party libraries and applications. In other areas (such as the kernel) Solaris is much more stable, reliable, and advanced. I build a new kernel every week or so from illumos-gate, and must say that the technologies in the kernel (ZFS, DTrace, kmdb, smf, zones, predictive self healing, process rights management) and some shipped in user-land by default (mdb, libumem, pfiles, coreadm, event ports, pmap) are cutting edge.

In the end it boils down to using the right tool/OS for the job :)