Timely Reinforcements can be a beating in the right deck. The card reminds me of another 3-mana card that saw play in W/B tokens back when Cruel Control was “the” deck in standard: Spectral Procession. Though the card has a pretty hefty drawback (needing to have fewer creatures than an opponent, less life), it seems rather swingy, especially surrounded by Battle Cry effects. Control decks can make very effective use of this card as well. Casting this the turn before a lethal alpha strike from Signal Pest and company, netting another turn of life, could mean the difference between stabilizing at 1 through a wrath effect or dying outright. Even if the card produces three guys or nets 6 life, the dire situation may necessitate it, and it may be enough to do the job.
Something else to consider when evaluating this card is that Hideaway lands have been out of standard for a looooooong time now. The hideaway lands really powered the W/B tokens deck in many respects, as it allowed the deck to power out some heavy hitters at a very substantial discount.
Will the card find a home in a deck? Probably. I don’t foresee anyone passing up on this kind of effect. Will it be a format-defining staple like Path to Exile, Spectral Procession, or the like? Probably not. The card isn’t quite good enough. A mono-white midrange deck that exploits Battle Cry may find the card useful, but its drawback will likely be its downfall. Strike two against the card is that it really doesn’t fit into Tempered Steel.dec (now watch me be horribly wrong). Battle Cry is an interesting mechanic that will see professionals tuning decks that include it. In fact, we are already seeing this to some extent. Contested War Zone, Hero of Bladehold, Hero of Oxid Ridge, and Signal Pest have all had top 8 appearances.
Quest decks may want to look into the card as well. Doh! Nevermind. We are a few weeks from the Innistrad release.