Fun! Level design is on par with the original game, voice acting is good, story is good, overall - Fun!

For the Emperor!

Found this game due to it's amazing soundtrack. Gameplay proved to be very fun as well.
And there's even a story mode! Story itself is unfinished, but even in it's current state it is very interesting.
I also finally understood why people enjoy using controllers thanks to this game.

The only desire I have is that the true tutorial was it's own option, separated from campaign, with tutorial's chapters available for replay and practice separately of each other. Because for me most stuff was easy, but parrying is hard and I'd like to replay those lessons as much as I need to understand the mechanic well.

A well made GAME. Has good story, well done maps, gunplay has received a great face-lift, so it's not default HL2. Everything makes sense.

Definitive edition Black Mesa is definitely prettier. It doesn't really show in Earth levels, but it shows heavily in Xen levels. It now feels much more moody, lush, and beautiful than it was - and it WAS beautiful before.
What caught my eye are godrays. I remember how Fallout 4 was marketing its godrays and other foggy stuff. And then you couldn't see it, because the game was a broken mess. This is not the case with Black Mesa. Godrays and fog and lighting effects are perfectly done and execute marvelously on my not-so-much powerful machine.
10/10.

Open World, Sandbox, kinda Post Apocalypse. If you like Mount and Blade - you will like this too. If you thought MnB was easy - you will LOVE this game.

Despite this game being Early Access one it already feels like a well fleshed out project. Don't let that "simple" artstyle deceive you.
If you like to build stuff - you will like it. If you like realism in your games - you will like it. If you like creating complex systems and tinkering with them - you will love this game.
One of the best things to me is native ability to configure your gameplay experience. You can switch off hunger, for instance, if you feel it bugs you and build your station in peace. You can increase the yield of ore processing so you don't have to mine a lot. And mods, they are natively supported too.
User support and bug-reporting/fixing is great. Almost each day something is fixed, added or remade to provide the best experience. Developers are easy to contact.

Buy it if you haven't done that yet.