I'm quite excited for the final release of Black Mesa, as someone who only completed the original Half-Life in the last few years (after it came to Linux) playing through a heavily improved version is going to be great.
Anyway, the Black Mesa team recently put out another progress report which shows off various work going towards the final release.
It's quite a short post though, giving only a few details on what they're working on like getting the Gonarch chapter fully "arted" with it now in the hands of their animators. On top of that, with the main Xen boss Nihilanth they've "made huge strides" including a full "feature set of attacks, defenses, AI, as well as effects". However, it sounds like they're keeping Nihilanth under wraps to not spoil it.
They also showed off some comparison shots of how it's looking (click for bigger):
You can find Black Mesa on Steam, currently in Early Access.