Disclaimer. I've been using Sun operating systems since SunOS 3.x or something, that goes some time back... unfortunately. Linux - since some 1993 for some times, now just following the development, but not using it at all - another matter entirely.
- I think it is a mistake to consider OpenSolaris answer to Linux - it is just a "productized" (sorry for the ugly word) snapshot of project Indiana . OpenSolaris is first and foremost Solaris - version 11. You still can use drivers on it as far back as Solaris 8 - they "just work". Show me other OS which can do this. The binary i/f are really stable.
- You can take a SXCR or released Solaris 10 DVD and add packages into an OpenSolaris installation generally without any problems. Again, they "just work".
- "Viable alternative" it ain't. It ain't alternative at all. It is an extremely good OS and a base to do whatever one expects from an OS - on it's own. You use it on it's own merits.
- The fact that it contains subset of the Solaris source code is irrelevant to the normal user (As opposed to OS developper). The bits not opensourced are mostly NDA-encumbered drivers which Sun is not able to release, as it simply does not own. The binary bits work with OpenSolaris, though.
- The point on application availability is valid on the surface - most of the open-source developpers work - and test - on Linux; sometimes it can be difficult to port these to any other Unix system. However, this can hardly be considered that big a hindrance - the important ones are working just as well.
- ZFS is, well, "the best thing since sliced bread", as they say here in Blighty. As you all know, it is now in Snow Leopard, FreeBSD, projects for other BSDs are in the pipeline as far as I know it.
- I haven't used DTrace a lot myself, just some supplied scripts, but again, good luck to Linux developpers in bringing something as good as it in the frame.
- I wouldn't recomment OpenSolaris to the casual user either - although it is easier than one could expect. One still needs to know what one is doing, unfortunately. But then, isn't this true for any OS? My personal experience with OpenSolaris 05/2008 could not have been better - on an HP nx6310 laptop the live CD booted fine, most of the hardware was recognized (no sound or wired Broadcom LAN at this stage, but see later), a few clicks and the OS was installed on a 4GB USB stick... I even cared to submit the results of the Device Driver utility to Sun and a few days later I got a reply that it has been accepted to the HCL and a pointers to the missing drivers (which I already had hunted myself).
- Long boot - give me a break. Solaris' is one of the fastest boots. Only the first one takes longer - the services get registered. Only my NetBSD installation boots faster.
- If you are after a decent development environment based on Solaris with DTrace and the rest, you better install SXDE or SXCR. You get everything, including the Ruby goodies - NetBeans 6.0 for PHP application has Rails aplication development on. In my view, this is the easiest way of getting the whole lot going. I haven't used Django, but "svn co..." and "python setup.py install" both executed without any errors.
- ZFS is not a developper tool, of course. It's just an excellent filesystem. OpenSolaris is the first wich actually installs itself in a ZFS root. SXCR still can't do this as of B90.
- Administration - the file locations are indeed different to Linux (and other Unixen as well - but we all know that). More important is to know that Solaris administration is somewhat different now - especially with the SMF. My switch from the wired office network to the wireless home one is a single line script - "svcadm disable network/physical:default && svcadm enable network/physical:nwam"... And vice-versa.
- BTW sound is from http://www.4front-tech.com/release/oss-solaris-v4.0-1015-i386.pkg , free but the license is for six months - you have to reinstall then.
This got a bit out of hand, but with a bit of luck may be useful to someone. Written on SXCR B90 running on the abovementioned nx6310, posted using the released Opera 9.50.