i think that they jut made this to create a sense of continuity for new gamers....they did say that people who havent played hl1 wont feel alientated ...but its probably for that anyway.
i cnat wait to finish both of them.
HL:S is only worth the extra money for people who haven't played Half-Life. Nothing new except ragdoll physics, pretty water, and some new sounds (the new sliding door sounds suck, in my opinion).