Let's start with the positives:
SFM cutscenes look decent for the most part
The story has potential and with some tweaking, could be pretty cool.
Now everything else:
Bad dialogue with voice acting ranging from fine to terrible. I especially loved that some US soldiers have British accents, which obviously doesn't make much sense. If they really wanted to have Alex Beltman and Pyrocynical in here, why couldn't they just make those soldiers actually British? Maybe just make them a part of some British team, sent out to help the US fight off the alien invasion or create some other explanation, now it's simply funny.
Bad graphics. Before release the developers talked about how this game's gonna look as good as Black Mesa (A remake of the original Half-Life) if not better. Well, Hunt Down The Freeman looks like those 2005 fan made maps for Half-Life 2, it's a mess of Half-Life 2 assets, Black Mesa assets, Left 4 Dead assets, Payday 2 assets and the ones the developers made themselves.
The Characters aren't interesting, the story is full of weird edgy dialogue and cliches, the game's ending cutscene is just prime meme material.
Gameplay doesn't really offer anything we haven't seen in the old Half-Life games. The only mechanic that stands out is the "Parkour System", which is useful like twice in the game, has janky animations and I wouldn't be surprised if it's actually just stolen from somewhere.
And finally. There is no Gordon Freeman. Yep, there is no Freeman in Hunt Down The Freeman. He is there on some cover arts. He is there in the trailer and the screenshots as well as in the "secret" ending, in which the guy's just chilling on some sofa.
Seriously, do not buy this. Go get Half-Life 1,2 or Black Mesa. This uhhh "game" is probably up there with Fallout: Brotherhood Of Steel and FlatOut 3 as one of the worst games I have ever played.