What are Romeo's strengths and flaws?

Romeo's great strength is his emotional energy and the way he throws himself 100 percent into living wholly in the moment. No one could ever accuse Romeo of doing anything halfway. When he is in love, he is completely in love. When Rosaline won't return his love, he mopes and moons around to the point his father is worried enough to start talking to Romeo's friends about what is going on. When the friends take Romeo to crash the Capulet party, he is determined that nobody in the universe could match Rosaline.
Of course, he immediately falls for Juliet. He falls so deeply in love with her that he thinks she shines more brightly than the stars in the Milky Way and the sun in the sky, and he wants to marry her the next day. In fact, he doesn't rest until they are secretly married. When they are together, he is heedless of the danger, and doesn't want to leave her.  Very few characters in literature live every moment as intensely as Romeo. He also is not one to pretend to be other than he is, and he never is wishy washy about what he feels or plans to do.
As with many people, the flip side of his strength is his flaw. Romeo's whole-hearted embrace of life means he often acts rashly or impulsively. It's great to be mindful of the present moment, but sometimes you need to step back and think for a minute. As the friar warns him, it can be a mistake to let your emotions run too high. You risk burn-out. Romeo never get the chance to experience burn-out, however, because he is too rash. In typical fashion, the moment he thinks Juliet is dead, he kills himself. We can all agree that was a mistake. Sometimes it's a good idea to step back and assess a situation before you act.