The messaging system doesn't work. The stats don't work. The search barely works. The ranking system is a joke. The invoices they send to clients are illegal in Europe.[https://community.upwork.com/t5/Clients/Name-on-a-received-invoice/m-p/92225#U92225]
And for the last few days, the job application system -- arguably, the most important thing on the whole website -- stopped working.
If you want to appreciate the full extend of the disaster, just visit their forum and see what their freelancers and clients have to say about it: https://community.upwork.com
They are already loosing people and the only reason anyone's still using them is the lack of a better alternative.
This is the perfect chance for a new platform.