It's fun and maybe it gives *a kick* if you can reach level 40 ...
... but for the rest it is very boring I think!
I can imagine if you're level 40 the Hall of Echoes and the final battle is a piece of cake!?
Even on my first hero that was ending this game at level 35 (almost 36) it was boring, above all in all the Flying Fortresses the Black Rings are with 1 blow or 1 magic spell killed! Totally NO challenge!