Don't overuse it for “annoying”: For a simple, fleeting annoyance, the single character
烦 (fán) is more common. For example, “This fly is so annoying!” would be “这只苍蝇真烦!” (Zhè zhī cāngying zhēn fán!). Using
烦躁 would imply the fly has put you into a full state of mental and physical agitation, which is an overstatement.