This is one of the few Submachine games that I actually finished without using a walkthrough (specially because there was no walkthrough at the moment) and it was worth it.
The map is too big and you need to remember all of it in order to finish it, which made the game kind of boring whenever you had no clue what to do, since you had to look in all the HUGE map to find a new object. Still, having the map being HUGE is kind of giving a grand finale to the series, and I, as a fan of Submachine liked it.
The HUGE map wasn't a big deal: since all items were clearly seen, you didn't need to focus on the map to notice them, so I don't think that you'll be finding yourself going back to look for items that you hadn't seen before, but going back just to use a new item that you already finded.
Finally, I think that the only thing that could be considered as bad for the game is the HUGE map, but, once again, it made things more enjoyable IMO, which is why I give this game 5/5 stars.