I suppose that at least it has synergy with Shiradi as those double rainbow procs and the Rain of Arrows amongst others do all kinds of elemental damage... My pure druid caster in Shiradi is pretty decent, 3 stacking HoTs and crazy random AOE elemental damage from all the AOE spells you can stack on a group of mobs while they are earthquaked, with the ice elemental debuffs on top for good measure.
If not going pure caster however i'm beginning to think that splashing 1 wizard for the cheap 1 ap = +40 spell power and free feat is much better than dumping AP in the actual druid spell power enhancements. Still haven't tried a melee druid build yet though...