Spell/Power Points DO have a (rather serious) problem: Spell Power is (should be) geometric for rather obvious reasons. Point cost is linear. That's not good.
The thing is, at the higher levels, a single 7th level spell (13 PP) is generally more powerful then two 4th level spells (14 PP), and a fourth level spell (7 PP) is more powerful then a third and a second level spell (8 PP), while at the lower levels, when Points are limited, a 2nd level spell is rather weaker then 3 first level spell. This causes a very extreme "Quadratic Warriors, Exponential Wizards" effect - Point-based casters can generally use much higher level spells then normal casters, eliminating the "Daily Ability" restriction on higher-level spells.