A ripe spaghetti squash will take some effort to cut through but it should be fairly easy once the rind is penetrated. If it's really tough, you might want to give it a few more days.
Slightly undercooking the squash may help in preserving that "spaghetti strand" look. I usually just microwave mine so I'm not too helpful in that regard.

I just wish it weren't so expensive!!!
Happy squash!!