enjoyable , if occasionally flawed , experiment 
(ROOT (NP (ADJP (ADJP (JJ enjoyable)) (, ,) (SBAR (IN if) (FRAG (FRAG (ADJP (RB occasionally)) (JJ flawed)))) (, ,)) (VB experiment)))
(ROOT (NP (ADJP (ADJP (JJ )) (, ) (SBAR (IN ) (FRAG (FRAG (ADJP (RB )) (JJ )))) (, )) (VB )))