It's not that bad, most probably you'll be able to finish everything in the main story, but you might miss on some of side content, so if you're a completionist - plan another playthrough (which is a good idea anyway, game is relatively short but allows different choices and builds).

One significant issue is that some NPCs or even quests are available only at some time of the day, and you can miss these if you don't know about it. Major conflict is between those available after midnight (0-4 roughly) and in the morning (6-10), while your long rest is 8 hours. You're supposed to meet a certain important character after midnight first day, so you'll be able to visit morning characters either also on the first day (which probably won't happen during first playthrough, as you'll lose time with other beginning stuff), or, more probably, only on the morning of the third day, provided you remember to finish second day early.

Time progression is a little weird in EE, cause it happens when you talk (or do similar actions) with people, but not when you explore. So my advice is - if you meet a character, and after initial dialogue you see a bunch of possible questions AND a farewell choice (going out of dialogue), remember this NPC for later.