It went pretty well. A small amount of extra oxygen needed once during the 2-year period. Ecosystems that shifted in unexpected ways but did not collapse. 100% sealed and self-sustaining is going to be very hard, but 98% is much easier and good enough for many purposes.
Yes, they failed every single one of their objectives, within weeks. They failed the psychological ones even harder than the others. (Whoever keeps pushing at a colony on Mars, should look at those later ones.)
But the GP also has a good point. They failed due to overambition more than to lack of results.
Getting people to live a month in a well-known but extremely harsh environment?
There's actually way fewer things that could go wrong than on the Biosphere experiment. Time exponentiates every failure mode, shorter times fix lots of things.
It may still be overambitious, we will only know after they try, but it's less ambitious than the other one.
