Over a year ago Oracle closed the source for OpenSolaris, leaving contributors outside of Oracle left in the cold. That was a huge problem for the adoption of Solaris which had finally begun to rise again. Recently Solaris 11 was released, but without the source, this was likewise a huge problem, but now also for enterprise customers who are using and paying for Solaris. DTrace have lost part of it's value for Solaris 11 compared to the now dead OpenSolaris.
A perhaps even large problem is that when Oracle closed Solaris, many, many of the core developers left Oracle. Several of them now works outside of Oracle contributing to illumos, but these changes can not be ported back into Solaris 11 as long as Oracle keeps the source closed.
Solaris 11 has features not available in illlumos, but I chose to use illumos instead of Solaris 11 since I have access to the source and I am not locked to one OS-distribution. Also the licensing for Solaris 11 does not allow me to use it for small deployments without buying a whole support contract. If I "upgrade" a zpool to use new features available only in Solaris 11 I will be unable to import the pool using the free ZFS implementation that in illumos based distributions such as OpenIndiana or Nexenta or other operating systems such as FreeBSD.
I think this is a terrible move by Oracle, not only are the alienating new customers, they are also locking out great engineers who have implemented revolutionary features into Solaris. As Bryan Cantrill pointed out in his LISA '11 speech, Oracle has not made any official announcement about what they have done to OpenSolaris or what their future plans for the source are, this is very troubling and ignorant.
Solaris 11 is a great OS but it being treated terribly by Oracle, Oracle seems to think that the best way to make a profit out of Solaris is to keep it closed for everyone else, I don't agree.
Talks I have given
2 weeks ago