Although many people bash Mashima for all his flaws on FT, I have to say that he is good at starting a new one. Initially I had doubts on Eden Zero because of Shiki's "befriending" nature and his characters template, but even so, Mashima is able to build an interesting story around the seemingly old concept of his.
So Edens Zero is basically adventure in space. Shiki, the lead, is an adopted son of "Demon King" (he looks like a robot - a major background character that is often mentioned). He was previously inhabiting a planet of automated amusement park, until, he met with Rebecca, a streamer (typically our twitch/ youtube star) came to the planet. After a brief incident, they finally starts traveling together. Along the way, they pick up new allies and find the ship Edens Zero (late Demon King's mothership) as they travel from one planet to another.
Personally I think Edens Zero has started the way Fairy Tail did, basically dragging me in with curiosity with what Mashima has in store for Shiki and co. His fan service is still there, it is part of his work anyway. Basically if you like FT or Rave and still want to see more of Mashima's work, this is a good try. Just don't hope it to become a long running sophisticated story like OP, and you're good to go.
Rated 8 for starters, though perhaps 7 would be safe bet for long run.
The following was added after series completion:
EZ is basically what you expect from a Mashima series, at times light hearted, ecchi, funny, goofy, but it can sometimes get dark. Essentially, it is space version of Rave. And if you love Mashima's previous work (particularly Rave), most likely you'll enjoy this one. Anyway, I put rating at 7 for being Mashima's work, but it's 10/10 classic Mashima imho.