I haven't played any of the other games, but I'm a good chunk into Untold (just got to the Third Stratum) and I'm really surprised. The game is clearly old school as well - you even have to draw your own map- but it feels new. I can't really place my finger on it, but I never really get annoyed when playing it (outside the odd back to back encounter), which is strange for something so rooted in the past. Honestly, it makes me want to play more of the series.
What's the forum got to say about it?