Quite fun! I liked the variety made possible by different block shapes and base numbers. Interest was extremely powerful, but that's probably ok; a lot of the relics seem like they can be extremely powerful so maybe that is part of the game's design.
Yes, I beat it the first playthrough. The only class I played was Samurai, which was fine although the Samurai-only relic I saw seemed pretty bad since it requires you to take damage and I don't think I took any damage in combat after the first half of the first level, and the other one which boosts swords if you only have swords is too much work for a measly one-time +1. I like the combo bonus for the samurai and it isn't too OP since the full-board bonus is even better and has relic support.