There are no fancy keywords on this card, just a straight-up old-fashioned value town. For only four mana you get a creature with flying, a life gain, and a card draw. That's exactly what a blue-white deck wants from its creatures. Simple and effective!
It also has an implied protection from all the bouncer spells, as you would be happy to replay it, which means that your opponents will think twice before casting any of those spells on Elite Guardmage.