The hastily cobbled together screenshot above really only gives you a small taste of the awesome that is Fire Nova. The old Fire Nova totem was okay... you'd drop it on big AoE packs if you could do so, but for a lot of shamans, sacrificing their active fire totem to so so was a lot to ask. The genius of Fire Nova, the new ability, is of course that it works with any fire totem you have. You're a restoration shaman with a Frost Resist totem down up close to the melee on Sapphiron? Well, our first question could be "Why are you still running Sapphiron?" but we'll assume it's a weekly raid thing. Anyway, even that Frost Resistance totem can now provide some damage! I'm not saying waste your mana on DPS if it's a tight thing, mind you, I'm just saying that if you found yourself healing a fight you way overgeared you can pop a couple of FN's in there to liven things up.
Yeah, okay, this happened to me. It was boring!
Where Fire Nova has really shined for me, though, is running a modified Enhancement set-up. Now, granted, some of the DPS I'm seeing from this has also come from getting a few upgrades to my gear set, but in tight AoE situations I'm seeing Fire Nova as a solid 2nd on the DPS chart, just behind melee attacks.