Just finished reading 70-Seas and the 70 Seas Extras. It definitely gives a bit more context to certain parts of Latchkey Kingdom! Overall, I enjoyed 70 Seas and right around chapter 10 I started seeing characters that appear somewhat prominently in Latchkey Kingdom. Meanwhile in the Extras there’s a bit more expansion on side characters (Snake Guy, Hilde) and some of the popular characters for patreon art requests that otherwise don’t show up much in LK or 70S’s main comics like the twin sisters and that Barbarian wizard slayer lady.
I will say though, the main comic is pretty solid and has a relatively consistent sense of humor that lines up pretty well with Latchkey Kingdom. The extras shift considerably in tone, though. Some are great. Some just don’t appeal to me. And well, there’s one or two jokes in 70 Seas that aged horribly. But still, overall more than worth $8!