Against a single target, this spell loses much of its flair. One-on-one, Living Bomb is essentially a pretty serious instant-cast DoT with a reasonably high damage coefficient. It isn't currently off the global cooldown, which makes it tougher to sandwich into most spell rotations. The spell description is currently misleading, as the knock-up effect seems to be happening not on the final tick of the spell, but whenever it pleases, including multiple times during the duration of a single application of the spell. I'm assuming this is a bug, but for now, it makes the spell incredibly unpredictable. It's a fairly mild effect as it stands now, similar in distance and appearance to making the enemy jump involuntarily.
But when you're fighting multiple targets at once...then we're talking about a whole different situation. That's where this spell excels, even in its current bug-ridden form. Each tick does significant damage (at level 70, with around 1000 spellpower, my Mage's Living Bombs were hitting for over 500 damage on each tick) to every nearby target. The knock-up effect hits everyone too. Aside from the damage, this means very good things for your typical glass cannon. Combined with the knock-back effect they've given to Blast Wave and the daze effect of Dragon's Breath, we now have multiple options for keeping multiple attackers from whaling on us while we kill them. Even spellcasters will hate this, as they never know when they might be interrupted in their casting by the knock-up mechanic. When soloing, this makes it far more manageable for a Fire Mage to handle multiple adds by simply nuking them down all at once. I can imagine it will work quite well for large trash pulls in raid situations, since the knock-up doesn't have enough distance to really cause any unwanted-pull problems, and yet it's interruptive enough to help keep the Mage casting it alive a bit longer.
Granted, increasing our AoE capabilities is not and never has been our fondest wish as Mages, and this spell seems focused on doing just that. The mana cost and global cooldown it triggers make it a bit too pricey to use to add DPS on boss targets, though its disruptive qualities make it an attractive PvP choice, even in one-on-one situations. It will have its uses in non-AoE situations, but it is absolutely meant for times when killing a group of things at the same time is called for. To be perfectly fair to the spell, it will fulfill that purpose incredibly well. Combine it with talents like Blast Wave (and its sweet new knock-back effect), Dragon's Breath, World in Flames, Hot Streak, even the very limited-use Firestarter, and you will find setting fire to crowds is even more recreational than you ever thought it could be. Here's hoping they fix the bugs, possibly lower the mana cost, and make this a spell a worthy 51 point talent for those of us who love to blow things up.