Just finished a few minutes ago. From a person that never finished other Bioware series other than ME, I think this ending not that bad.

The cycle that has happens millions of years and destroyed thousands of advanced civilizations at last ended by Shepherd is a great achievement itself and I personally felt quite satisfied.

Although we do not know what happened to other character that we invested a lot is a bit unsatisfying and feel somewhat incomplete. Probably some "milky" dlc will answer this. But overall this series is a great adventure for me and if this is the ending Bioware want to present then so be it.