I'll just go out with a small general warning here. Although my last post about druids were about tanking issues, this one will be of something completely else. I thought they had buffed lowbie casters so that it would be less of a hazzle to level one. And for most of the casters out there, this is true. But not so for Boomkins. Unless you have the possibility to use BoA gear, I advice against leveling as a boomkin, the first 40 levels. Because unlike every other caster nowadays, boomkins don't get their mana regen until that level.
One could think that this has something to do with the fact that Innervate is usable on others and not just yourself, but I can't see how this could be so OP that the poor druids can't have it already at level 20, or around there, like every other caster get their regen skill? Considering most mana regen skills have dropped more than 40 levels, dropping Innervate some levels doesn't really feel like too much to ask for. The shaman water shield was obtainable at level 62ish before, and now you get it at 20. Evocation was level 40ish, and now level 20. Only ones who are even more unlucky are paladins, who don't get Divine Plea before level 71. But on the other hand there are no caster dps paladin specs (or are there?!), which means they don't really have this problem. And besides, they have blessing of wisdom and seal of wisdom and judgement of wisdom! Don't you dare feel sorry for a paladin. Priests get Spirit Tap in the very first tier of the shadow tree. It is clear that mana regen is something very important for casters.
Being a caster at low levels is still more of a challenge than melee classes. Especially when instancing, where you will constantly oom. But no one has as much mana issues as a boomkin.
Oh and another thing, boomkins don't get their aoe until level 40 either. Every other caster class, who has an aoe, get them way earlier. Shadow priests don't get mind sear until level 75, but on the other hand they at least have holy nova, which even is glyphable to do more damage.
Yet again it feels like druids have been put aside by the designer team. All these problems become a little less annoying if you're boa geared, but I'd recommend anyone leveling a druid to do it as feral, at least until level 40. As feral you'll run faster, do good damage in instances (and outside) and be able to tank which means you'll get groups instantly. All win.