Not quite what I'd been hoping for.
The positives: They absolutely nailed the combat physics and the sim-heavy control scheme, while the flexibility in loadouts runs so contrary to modern day "water it down" sensibilities that it made me smile. I also appreciate what they're trying to do in making the campaign open-ended: as in 90s games like "X-COM: UFO Defense", you can totally screw yourself in "MechWarrior 5", which I love. The game seems like it's built with "infinite replayability" and starting over in mind.
The negatives: No "RTX" features yet. Beyond that, the game is a total mess graphically: dithered and banded lighting, totally messed up "level of detail" functionality, and the worst temporal anti-aliasing I've ever seen. Thankfully, people on Reddit have been hacking the .ini file to good effect. The "game around the game" also feels only half-finished: the campaign has some bizarre balancing, there is a huge hangar to walk around in but nothing in it, and so forth.
All-in-all, it kind of feels like an "early access" game in its first release. I know they are selling it for 50 USD and not the usual triple-A 60, but still...
This is one of those games that's going to get a lot better with patches; it'll be a totally different game in six months.