I am going to play on medium, but I am considering playing on hard.
I have only played Half-Life once (as the whole series), and that game was indescribable. There are no words to describe how great the game is. I have been itching to just load the first level of HL, but I am saving it all for Black Mesa. I feel like the experience is going to be very awesome, remembering things from the game and seeing and hearing them in a new way. I am happy the devs made changes to some levels, as we can discover new places and feel like we are playing a new game while at the same time reliving one of the best games ever made.