Since you can't read: Yes, I have actually played and completed the game recently. It is the same game. Sure, they did change it a bit. They replaced HEV Suit's voice just for the sake of replacing it. They... added some dynamic shadows? Now the boring lighting is unnoticeably improved, but still boring. Where in this did the game suddenly transform into something incomparable to the original release?
You just started by saying "I PLAYED THIS SEVERAL TIMES BACK WHEN IT WAS A MOD", so people assumed that was when you'd last played it. It was only after I posted that you clarified that you'd played a more recent version. Major communication breakdown, Unreal, and it's all your fault!
It's no longer really comparable to the mod release because the difficulty/balance has changed, the Marine AI has radically changed, some alien enemies now have new behaviours and abilities (vortigaunt doing the annoying Skaarj-like dodge), several levels have been reworked (mostly for the worse IMO), Xen is now about half the game for better or for worse, there's been a lot of graphical changes (didn't they move to an entirely different build of the Source engine at some point?), the weapon animations and sounds are different... I get the feeling they've also changed the amount of enemies in some levels.
It was worse than I remembered. I know, that's ‘subjective’, but it still bothered me somewhat, even back then. The graphics are undeniably amateurish. They're high fidelity, but the aesthetic feels off, even for what it's trying to be. The modern cinematic style was never appropriate for Half-Life, anyway. Half-Life 2's visuals were really the more proper evolution of the series. Black Mesa just looks like a boring Xbox 360 game, but worse. The tone is lost with the ‘emotional’ music and boring voice acting. Their performances just sound so flat, which was rather surprising, really. I didn't remember it being that bad. Well, except for the stupid things they did with the Marines and the announcement system. We can't just have an amusing scene involving a falling elevator, no, it's gotta be some fake dramatic Hollywood shit. The whole game acts like that, and it's really distasteful.
The graphics are probably about as good as anyone's gonna get from an antiquated pile of shit like the Source engine. It is indeed subjective but I think the aesthetic is great - I genuinely can't see what more they could have done. Half-Life has a lot of rooms that are oddly empty but where the intent is clear, and all Black Mesa does is act on that intent - the best example is Residue Processing, where the sparse central room of Half-Life is reworked into something that makes a lot more sense as a waste treatment facility with lots of entrances and exits, catwalks, control rooms etc. The old decommissioned areas of the facility from Blast Pit through to Apprehension look really great at times with all the rusted cold war computers and machinery.
They take a lot more liberties in Surface Tension but IMO it largely pays off with some visually impressive areas and new puzzle rooms that are fun to play and fit right into Half-Life's design philosophy.
I don't think "the whole game" puts in tryhard dramatic Hollywood shit. There's some of it but it's very sparse - the only part I can think of is the completely fucking awful part where you have to sneak through the aircraft hangar with the guard at the end of Surface Tension. Most of the game is just a one-for-one remake. I suppose you could describe some of the new scenes like the ambush at the end of Questionable Ethics as "Hollywood shit" but I don't think that one is a huge departure in tone from Half-Life.
The Marine sounds actually changed one last time in the new update and they have deep obscured voices now. Still don't sound as good as they did in Half-Life but it's a lot better than the lame nerd voice they had in previous builds. VOX sounds alright to me. The soundtrack is definitely one of the biggest weak points, the terrible orchestral shit is incalculably worse than the original industrial/techno stuff.