Getting to set up your graveyard on turn one for a Vengeance on turn two is something the Esper variant is incapable of
Worst-case scenario, you can flash it in at the end of your opponents turn and start attacking
Part of why this is so playable is that blue is very thin on the ground for good playable aggressive one and two drops and while this does not scream aggression it is a fantastic support dork and scales very well with equipment and other pump effects
While we already saw the power of Thalia in powered formats, where she can hate out combo decks and slow down sweepers, such as in the Five-Color Humans deck above, the card has also enjoyed a great deal of success as just a good card for aggressive, creature-heavy decks. Creatures (27) 3 Fiend Hunter 4 Champion of the Parish 3 Avacyn's Pilgrim 3 Mayor of Avabruck 3 Thalia, Guardian of Thraben 2 Restoration Angel 3 Sigarda, Host of Herons 4 Silverblade Paladin 2 Druid's Familiar Lands (25) Spells (8) While Thalias ability is so good, she would likely see a fair bit of play even without first strike, its actually the first strike that really gets her over the finish line
If you want to see how different cards fit into your Magic: The Gathering deck, making proxies allows you to test out new play styles
(Not available in Draft Boosters.)