Hated Xen anyways in the original so it feels like I got the whole game here already pretty much.
I'm really impressed, a few hours in... they added TONS of extra details. I'd say it seriously looks better than the HL2 games. Granted it's newer, but for a remake made by fans, damn... it's really really good.
Just from the first 20 minutes of the game. I knew it would have the capacity to change lives. I know the second half of the game will be just as good.