I've had the same experience. Copilot for Excel can't even parse basic cell references. Meanwhile Claude handles document formatting in one pass. The catch is it works externally, not inside the app, but at least it works.
The MCP ecosystem is what makes this interesting. Claude isn't just a chat panel bolted onto existing software, it's building integrations that actually manipulate the files. Microsoft had the distribution advantage but they're losing on capability.
I would consider myself an M365 power user and I was not aware of this. It is not well promoted--and after all the Copilot crap, I would be annoyed even if it was.
Regardless, I just tried to log in with my work MS account, and I can't do so.
The MCP ecosystem is what makes this interesting. Claude isn't just a chat panel bolted onto existing software, it's building integrations that actually manipulate the files. Microsoft had the distribution advantage but they're losing on capability.