Indeed, I almost stopped watching after the first four episodes or so because it felt like it was going to be "the Mariner show" and Mariner was really rubbing me the wrong way, she was a very annoying character. But the show course corrected over time, it brought several other main characters up to equal prominence and more importantly it started filing the annoying edges off of Mariner to make her a more well-rounded character that I actually kind of like now.
Now it's my top recommendation for modern Trek. And for Trek in general, really. The people making Lower Decks are clearly deeply in love with the setting and its history as a show.