I loved that first encounter with the marines. I clearly remember how I tried to camp behind a wall expecting them to stroll in one by one and pick them off and was shocked when they lobbed a bunch of grenades in instead.
I'll be playing it on hard anyway, i'll probably end up taking a lot more than 20 hours.
Even otherwise, 20 hours of solid gaming without halo style corridor after corridor of giant TVs should be very satisfying.
Indications that the game will go gold tomorrow (or in the next couple of days):
1. CS:S will be released next week.
2. Magazines have reviews coming out next week.
3. Ign says the gold disk has been delivered to VUG.
4. It's Sep 30.
If the game goes gold and they announce a ship date, people who want to buy it in stores will likely hold back. If there is still this uncertainity over when the game is going to go gold, they will lose customers.
If they are releasing CS:S on steam next week to Steam customers, VUG will want to release the game ASAP cause they are gonna start losing sales to people who can't wait.
Nice move by Valve :P