I usually try to put a lot of elementals in my deck so I do not have to worry about the chain breaking easily. I have little use for an understated card like this. I guess it is useful in priest with Lyra and Quartz Elemental. It can also be used in Mage for Bonfire Elemental and Shaman for Bogshaper for deck thinning.
Gnomish Inventor showed us that 4 mana 2/4 card draw is hard to justify. I don't think it will make a cut, especially considering that it is not elemental itself and elemental decks rely on the non-stop elemental chains.
Actually, back in the day Gnomish Inventor saw play in the original, combo version of Patron Warrior, and it drew any card. With the added restriction of only drawing elementals, I could very well see this being played in a combo deck where you only have one or two elementals that your win condition revolves around.
It would be underwhelming if this pulls you one of your fire flies. That's why I think the card is more powerful not in elemental deck but decks that run few elementals that are if not crucial, let's say more important than average minion. e.g. Gedon /Rag/ Leyline for Jaina, Lyra / radiant elemental for priest, Rag, lightlord for control pala. I think the card is very good.