I'm not sure how high your standards are but the goal is for XC to be bulletproof by Rev 3. And at their current (early) stage of development XC is solid, and working.
Lastly if you keep up with the XC team you'll know that these future-oriented announcements are not said lightly. We're under a lot of pressure because people's expectations are very high; the price will crash very hard if we're even late for an update, never mind if we were to fail. So we do not make promises we're not confident we can deliver on.
All I see on the site are binaries - is it closed source???
No.
XC recently released the code for the Rev 1 (trusted) mixer (which KeyCoin has happily adopted).
XC is currently using its Rev 2 trustless mixer (which is a world-first).
Here's XC's stance on open-source:
Q: Is XC open sourced?
A: XC is committed to the open source model. Open source code is vital for the health and advancement of cryptographic technologies, and it is a privilege to share our technical breakthroughs with a community such as this. We believe that XC's code embodies several world-firsts enabling anonymity that is scalable, mobile-friendly, POS-integrated, and is ultimately a platform upon which a broad range of Blockchain 2.0 technologies will be built.
However people’s faith in cryptocurrency projects is significantly hindered by clones. Therefore we believe that the ethical way to engage with the community is to make our code available on a delayed timeline. This way, the community will still benefit from our work, while we'd reduce the incentive for developers to flood the marketplace with clones that lack a long term future and reduce the trustworthiness of the altcoin phenomenon. XC represents several market-leading innovations, and we are honoured to make these available to the community in the near future.
http://xc-official.com/faq-page/