It's decent enough for me to use it instead of Google Docs but it definitely has it's limitations. While Google Docs seems to render things on the client side,

It's decent enough for me to use it instead of Google Docs but it definitely has it's limitations. While Google Docs seems to render things on the client side, Collabora Online renders everything on server side, which makes this uncomfortable to use with slow internet. While the feature set of Collabora Online is decent, there are some missing, for examples you can't insert/edit mathematical equations and there are no macros. Templates are supported but you have to create them externally and then upload them. I think it's good enough to write a few pages of text but it's not good enough for power users who write 100-page essays or use complex formatting.