I played through Etrian Untold late too, and really enjoyed it. The new area they added in - I think it was called Gladsheim - complemented the adventure perfectly while also being an interesting dungeon with a new twist in every floor. The presentation is also top notch - excellent use of 3D to layer the menus, and it really added a sense of place when exploring dungeons.
If you haven’t played it yet, do check out Etrian Odyssey IV - it has the most inventive dungeon design in the series, and the world map itself is an enjoyable metagame dungeon where you have to plan your movement based on FOE behaviour and terrain. Unlike the other games in the series dungeons in IV can have varying amounts of floors and shapes, and they can even have several entrances from the world map! The only blight to IV is the unremarkable 3D in dungeons - it looks like a 2D image pushed into the background (Layered menus still look great). They’d improve upon that massively with Untold of course.
One of my favourite things about the series is the second-person narrative and minimal use of spoken dialogue, it really feels like an adventure where your imagination fills in the gaps.