The second and last Expansion for Half-Life is good but it's a small step down.
Blue Shift only have eight chapters witch makes it shorter than Opposing Force and there isn't any new weapons or enemies and you spend most of the game inside the facility again so it's almost like a map pack for Half-Life.
I Don't have much to say about this game other than it's Half-Life all over again only way shorter, but it's cool to see the Black Mesa incident from the perspective from Gordon, Adrian and especially Barney because he comes back in Half-Life 2 and you will have no idea who it is so it's good that Barney have a back story but i think that they could have at least given you some new weapons, at least a different melee weapon than the crowbar.
The controls is the same and it's still a little slippery and the sound in the same as Half-Life so there isn't anything new at all.
If you are a true Half-Life fan you need to play this but if you expect something new, don't bother.