Cemetery Gatekeeper seems like a very strong aggressive mono-red two-drop. If you’re able to ever exile a land, particularly on the second turn, this becomes an extremely powerful card. Of course, it’s symmetrical, but if you’re playing a red aggressive deck, you should be able to get a lot of value here. The natural tension here though is that cards like Evolving Wilds tend to be weak in aggressive decks, since it’s effectively a land that comes into play tapped and we have to play off curve.
Let’s not forget though – a 2/1 first strike with upside is already pretty strong. This card is also just a built-in hate card against combo decks. Exiling instants is good against control decks. Even playing something like a Shock on a turn one creature and then exiling it should be good against creature-based decks.
In addition to being a solid 2/1 on curve, Cemetery Gatekeeper is a Vampire as well, capable of getting benefits and synergies from “Vampires matters” cards. Also, just the ability for a 2/1 to exile a card from a graveyard is decent by itself. Plenty of decks, or at least cards, use the graveyard, and having some built-in hate against it is pretty strong. If mono-red is good when Crimson Vow releases, or if Cemetery Gatekeeper is particularly hateful against some decks that surface, I’d expect it to be a pretty popular card.