DLC has become a dirty word for a lot of people. Seeing DLC for a game usually means you're going to be greeted with multiple $0.50 - $15 purchases for cosmetics, power-ups, and individual characters or maps. Or you're paying for the shaky "promise" of DLC that may be released later and may not be worth the money.
Legacy of the Moonspell isn't any of that. It's an expansion pack that comes with new characters, weapons, music, secrets, a map, and an adventure. For $2. There are no lootboxes, micro-transactions, or 0.00001% RNG drops here. It's more Vampire Survivors fun.
This is the first DLC that was released for the game, so it's a little lacking compared to the newer ones. However, it's very good and well-worth the price! The main characters each have some unique (and powerful) mechanics which are fun to experiment with. The map is definitely a change from the usual fare. It isn't an endlessly scrolling screen, and different enemies spawn in different areas of the map. You'll need to keep this in mind for some of the unlocks.
This is a definite recommendation from me.