You obviously have to decide this for yourself--reflect back about how you reacted to Hamlet's actions, his conversations and his soliloquys to better decide what your focus will be. What some people regard as his weakness, someone else may admire. You will need to explain and support your stance.
Here are a few things to think about that I think are key to understanding Hamlet strengths and weaknesses.
1. Hamlet has a deep and abiding inner moral compass. He wouldn't commit suicide, he loathes his mother's hasty and rather incestuous remarriage, and he worries about the after life.
2. He is very philosophical -- look especially at his comments about the flaws in human's when he talks to Horatio in Act 1 and his "to be or not to be" soliloquy in particular, but also moments of all of his soliloquys could be considered "thoughtful."
3. He is very loyal to his father and his memory. He desparately wants to avenge his death, especially after he assures himself that the ghost's claims were true.
4. He does seem to love Ophelia as revealed by his actions in Act 5, but his behavior earlier in the play can be a little troubling -- he is pretty hard on her in Act 3.
5. He is deeply depressed about the state of his life and Denmark.
6. He calls himself a coward, but is he?
7. He is well rounded: an intellectual, a man interested in the theatre arts, a talented fencer, a philosopher of sorts.
It might be intersting to see if there is a strength that becomes a weakness or vice versa. The complexity of Hamlet's character -- that it isn't easy to pin a single label on him-- is what makes this such an enduring play!