On the subject of Etrian Odyssey - Ghaleon more or less nailed it for the first one, where a couple abilities were horrifically overpowered (Immunize & Defender or Shelter would make a party nearly immortal, maxed Relaxing could have you walking out of FOE battles with more TP than you started with), but if you didn't use them, the game was really difficult. And still, at the very end, there was still some exceptionally tough challenges - even with those skills helping out, the postgame really required you to know exactly what the hell you were doing.
EO2 took away the overpowered abilities completely (Defender stayed, but it wasn't quite as awesome), and a lot of bosses had tricks outside of just pure damage to drive you nuts (Bosses confusing your whole party on the first turn anyone, and god forbid you had a Troubadour in the party facing the Colossus), not to mention FOEs being way scarier. There was still a way to break the game (This time it was Hexers), but for the most part the game stayed challenging throughout because no other class was an easy-mode button; in return though the aftergame was apprently not quite as bullshit as it was previously, excluding the very last rageboss of course.
EO2's probably a better comparison to LoT. Overall the game is tough in both instances, but a little bit of understanding and carefully building your party (In EO2 meaning proper skill selection, in LoT meaning party selection), you could get through pretty much anything.
