Totally depends on your build and your playstyle. There is no 'typical' Daggerspell Mage. Some pick it up just to get sneak attack for their Warlock while keeping caster level progression; others will play it like a gish (casting buffs first, then going into melee with touch spells+dagger attacks); still others will play it like a sneaky caster (conserving spells where skills can do the trick and vice versa)... just decide what you want to do!