Jason had a printed out sort of PDF preview they'd provided the authors with. I don't think it was complete, but it was enough for him to run with.
My cheat sheet explains the basic differences. Without going overly detailed, here are a few things that come to mind.
Dex is used for both Attack and Defense rolls (yes, you roll Defense + d20 to avoid getting hit). You can parry or dodge, which are effectively the same thing depending on circumstances, or if you have a shield, you can block, which gives you a bonus to the roll based on shield size (I think there are feats that help here as well). Since Defense seems to trail Attack, having a shield is a good thing.
Armor reduces damage. The scaling on it seems quite realistic in that my character (a knight in mail) was able to hold his own against longsword armored brigands despite being outnumbered and hit a couple of times (I took 4 HP damage from a fight I entered at 3 to one odds, and that was due to a crit), while my greatsword wrought bloody havoc on the leather armored bad guys (seriously, it was quick and ugly).
Crits (even tiny ones like the one my guy took) are serious business, because they keep on bleeding until staunched. I was very glad to have a Maester handy after the fight and more than glad to have left him behind to watch the pack animals while we counter-ambushed the brigands.
Characters have a Shock trait. If you take that much damage (after armor) or more from a single hit, you have to make a Fort save to stay up and useful. It's a pretty small number, all in all. There are feats to improve your own Shock and to temporarily reduce the value of others.
Hit points are rare and very much tied to the combat capabilities of the character. My knight (a 4th level man at arms/2nd level knight) had 42 starting HP. The 5th level minstrel sitting next to me had 13. The fifth level Maester accompanying us had a whopping 10.
Skills have specializations which give a +1 modifier under applicable circumstances.
Characters can also take training in particular professions that grants bonuses. For instance, my guy had "Armor Compatibility" which gave him an extra point of protection from his mail. Having spend a good deal of my 20s and 30s wearing armor and running around tourney fields in the SCA, I thought this was a nice touch; in my experience, it is very possible to learn to use your armor in a way that optimizes its protection.
Characters have three additional social traits: Reputations, Status, and Influence. We didn't really play with these mechanically, though my guy's "fierce" reputation helped force a quick surrender from the bandits we fought.
Looking through the rules, it appears that Maesters have lots of class abilities that allow them significant adds to roles pertaining to lore and knowledge skills.
There are a number of Clan based feats with evocative names like "Winter is Coming", "Hear Me Roar", and "We Do Not Sow", which have cool effects that I'm not going to go into.
The PDF printout was black and white, but it was still quite lovely. He had a printout of the full color character sheet and I liked it a lot. It's clean and easy to find stuff on, but it's evocative and doesn't look like a spreadsheet.
