It is so secure/anonymous and private that you can’t even see the amount transacted between the different parties. Even law enforcement people weren’t able to find how much Monero the Alphabay owner had at the time of shutdown.
https://www.wired.com/story/monero-privacy/
The Dark Web’s Favorite Currency Is Less Untraceable Than It Seems
That shouldn’t just worry anyone trying to stealthily spend Monero today. It also means evidence of earlier not-quite-untraceable payments remain carved into Monero’s blockchain for years to come, visible for any snoop that cares to look.