I think it's good AgentJ what do you mean by solid character
He was a rival, and a better-than-average one at that. Naruto and Sasuke seemed to have a healthy relationship founded on the classic "overachiever vs underdog", with just a hint of comrade re building subtly over time. The Zabuza arc did a brilliant job of fleshing out what our main characters were, as well as believably progressing them along their own paths.
I was also a fan of the jonin (or was it chuunin?) arc, where Kishimoto set the stage for what would come in the pre-time skip future. Sasuke meets Orochimaru and has to start dealing with his curse, which becomes part of his growing inferiority complex with Naruto. Sasuke has been the best at what he does for most of his life, and now he's beginning to be overshadowed by someone that wasn't even on his radar before. I'm sure most people can identify with his feelings as he lies powerless to help while his "rival" succeeds in his place.
His motivations for leaving are strong, there's no denying that. But his character was never better after he left. Would it have been cliche for Sasuke to change his mind after the waterfall fight? Absolutely. But I would have vastly preferred cliche over another cold, brooding psychopath with a heavy grudge. The character completely changes without a convincing reason. Before, Sasuke was like any other good character in fiction. He was somewhat likable, had strong points, but also had obvious weaknesses and deficiencies. He was real. And even as the antithesis of the main character, he grew on the audience over time. But after the time skip, he becomes generic, single-minded, and two-dimensional. He isn't "real" any more. His character is definied by taking revenge, without any other side to him. The reason why so many liked Itachi is because there was more to him (not to mention the nail polish and fish-nets). His motivations were interesting.
What I'm saying is that Sasuke needed to come back to team 7 at some point, for all the same reasons that it was powerful to leave in the first place. He was a puzzle piece, a necessary aspect in Naruto's and Sakura's lives. And while that made his betrayal compelling, it also stunted the series irreparably. Ideally, after beating Naruto at the waterfall, Sasuke would have realized what was going on and carried Naruto back to the village, understanding that he, like Naruto, has made friends among his peers. I'm still hoping that at some point in the near future this is what takes place, but at this point, he has probably done too much to ever be accepted again. And if they do welcome him back with open arms, that will be some bad writing. A plot-hole, even. :P