Eh, it seems like you'd be vastly more excited about a standard 1 mana deal 2 damage spell like holy smite or arcane shot. This is clearly a tier below those in terms of early game removal, not only does it cost 2 instead of 1 but you're also taking face damage. Best case scenario is probably a net heal of 1 since you have to A) be damaged already and B) hit something small. Most of the time you use it on turn 2, you're probably taking damage.
The other use is that it can also be a survival card in the late game, heal 4 and deal 2 damage to face. Obviously you would rather have a holy light here though.
It's saving grace is that it can be functional in both situations. Whether that's good enough to be a commonly played card, I dunno. Like you say, it might be necessary, but I'm definitely not excited about it.
Holy light is actually used in Pally because it trigger off Pyromancer as well as giving you some time to get to that consecrate+equality. This card is like 10x times better in every single situations unless some extremely fringe ones like on an empty board, opponent at 3 and you both on 5 fatigue damage next turn. Or something less fringe like against a VoidWalker and without anything on board in which case it just heal 4 instead of 6. But there are so many case where this is insane compared to holy light (an actual played paladin card because pally early game sucks):
- early on vs a midly devoleped hunter board, kill their madscientist/knife juggler, gain 4, that's a huge swing of tempo, you basically timewalked
- turn 3 kill a creeper, turn 4 consacrate clear all
- against a sylvanas with a Truesilver Champion, you can clear Sylvanas with no minions on board.
- lategame it's the same life swing as holy light, but can deal 2 directly, remove a taunt totem, or just kill someone directly
And yeah, if arcane shot was available for pally it'd probably be played , but this is possibly better because the lifegain is more important for slower decks and the attack part is crucial to stabilize the early game, especially given how paladin had 0 way to slow down the board earlier outside of humility and the 3/3 that cast humility. Combined with the new 2/2 divine shield, pally has now actually decent stabilizing power, too bad its lategame is still pretty medicore compared to other control class (warrior with the best early game clears weapons + whirlwinds effects, WL with infinite card drawing + giants, and druids with AoL, SavageRoar combo and now mr. Ican'tgetdecked Malorne).