Anonymous transactions on a blockchain are a big deal and has been subject of research in the last few years, now DASH claims that its built-in mixing ability (darksend) is anonymous, I'm wondering how anonymous is it, say compared to a coin mixing service, which from my research is not actually that anonymous. Thanks for any info.
Its fully anonymous in a decentralised way, integrated on protocol level and is optional. It uses a thoroughly improved and adjusted CoinJoin to accomplish that.
Compared to a coin mixing service it is a lot more decentralised and does not have the risks associated with centralised mixing services.
In its total existance Darksend (renamed to PrivateSend recentely) has never been broken and the vulnerabilities that were found by an external audit from Kristov Atlas in 2014 (when it was still closed source) were quickly patched up and Darksend has been opensourced soon after that.
Update 12.1 (in development) is focussing on making the whole Darksend / Privatesend proces more efficient and faster, its currently undergoing testing on Testnet.