As you may know, I've posted my thoughts on Itachi, Sasuke and Naruto before, and I consider them as the main characters in the anime. Since they are so vital to the story and the most popular characters, I got the idea to present to you how I look at them.
Starting with Uchiha Itachi.

He's without a doubt the most mysterious character to date. We don't know much about his reasons for killing the Uchiha-clan, nor do we know what his goals are. Of course, we can guess, but there's so much uncertainty about this character that it will probably not be reasonable.
He's presented as one of the most gifted shinobi ever, and scared even Orochimaru at a very young age. What is his purpose? Why did he join Akatsuki? There must be something that triggered his actions towards his family, friends and supervisors. Not to mention his beliefs. I have a strong feeling that he didn't keep Sasuke alive just so Sasuke could avenge him.
Now, to my next point. There's very little information revealing how strong he really is. His secrets are almost infinite. Never have we seen any sign of him being tired. So I most curious at how far he can go if he's pressured. I'm well aware of his meeting with Jiraiya, but it seemed to me that he got away pretty easy. I hope this is common knowledge, the fact that not many will openly show their training methods and so and on to the opponent/competitor. It's my beliefs that Itachi knows he can kill Jiraiya, but he won't share this with anyone, not even his fellow Akatsuki members. He's not stupid(after all, he has seen much with the sharingan:amuse) and Jiraiya is one of the most experienced shinobis alive, so of course it's going to be tough, but in the end Itachi will stand victorious. I fancy Jiraiya alot, but just imagine how far Itachi has reached. He's not the type who boasts about his power, and he knows that it's dangerous to be too arrogant. Remember when he talked to Sasuke about this? Yet he's always so confident. It is with this that I believe he has uncovered a secret that makes him almost unbeatable.

Can't wait to see more of this awesome character.