challenging, provocative, interesting, enigmatic, mysteried, mysterious, curious, mystic, puzzling, ambagious, more...

dull, boring, uninteresting, blah

interesting, fascinating, engaging, captivating, absorbing, more...

most interesting,   curiosity inducing,   drawing you in,   inspiring curiosity,   that excites me,   very fascinating,   makes you wonder,   interesti g,   what is interesting,   this is interesting