This is going to be a very difficult question to answer, because Hamlet as a character has managed to provoke much discussion and debate amongst critics in the last few centuries, so trying to condense his character into two or three phrases is a very challenging task to accomplish. In addition, people will answer this question based on their own reading and understanding of Hamlet, so in a sense, it is important that you try to answer this question yourself in addition to using the ideas of others.
For me, when I think of Hamlet, I would have to associate the following characteristics with him. Firstly, he is indecisive and procrastinates. He spends so much time wandering whether or not to act and what to do in response to the Ghost's words. This of course leads him to judge himself harshly against other examples of action such as Fortinbrass.
Secondly, he is spied upon and betrayed. It is hard not to feel sympathy for Hamlet in this regard. Everyone whom he had trusted and loved seem to turn against him and are used by Claudius in a plot to work out what is wrong with Hamlet. The only person who remains true to him is Horatio.
Lastly, he is seriously depressed and questioning his existence. Hamlet is famous for his big existential dilemmas as he debates his purpose in life and contemplates suicide.