Overall, the rules have a very OD&D feel to me.
Mapping saves and skills as attribute checks seems pretty solid to me, very old school.
I'll admit I'm a little concerned about their flat math. You need big bonuses to make a difference when your random factor is a d20.
The advantage/disadvantage (roll twice, take the better/worse) mechanic is nice. I'm looking forward to seeing that in play. Much more gratifying than a small bonus and doesn't complicate things by stacking.
Their line on buying magical items is up my alley (i.e. you can't).
Not sure I'm sold on their approach to rituals (exchanging components for memorization), but it's certainly worth taking for a spin.
Scaling spell effects based on the target's hit points makes "save or suck" way more interactive with the rest of the party. Very cool.
The spell effects look perfect too. They're short and easy to understand without being too jargony.
Overall, lots of simplification. It should be fun, but I'm sure it still has a lot to hammer out.
Cheers!
Kinak