audacious, courageous, dauntless
bold
capricious, mercurial, volatile
changing quickly
dither, oscillate, teeter, vacillate, waver
hesitate
abrupt, apace, headlong, impetuous, precipitate
act quickly
credulous, gullible, ingenuous, naive, novitiate, tyro
innocent/inexperienced
abstruse, bemusing, esoteric, opaque, recondite, ambiguous, cryptic, inscrutable, paradoxical, turbid, arcane, enigmatic, obscure, perplexing
difficult to understand
articulate, evident, pellucid, cogent, limpid, eloquent, lucid
easy to understand
astute, canny, erudite, perspicuous
smart/learned