A nice book for a quick foray into elemental classing. 5 'elements', one of which works very well for merciful characters or in games where outright murder isn't the goal. Additionally, the class offers a pet option: the Elemental Guide, which functions as a short term summon and semi-familiar rolled into one. As a source for character flavor, or alternately a hook for the storyteller to bring in new elements, it's a nicely made book with enough material to add to, but not break, the session.
From a mechanical point of view, there are a few great options, as well as a handful of rare/useless ones. Then again, variety is the spice of life and a clever or driven character can make use of even the most 'harmless' of things.
The two most interesting options offered, in my mind, are the Elemental Pact of Love (which actively discourages killing or lethal intent) and the Swarm Elementalist (which summons a horde of tiny elements rather than a single being). Both offer interesting play options as well as character ploys with enough flair and benefit to make their respective weaknesses a tempting offer.
Overall, a nice book with a decent enough variety to warrant the $6.99 price tag.