@Fire Fist:
Well, the only character to "leave" the series in Bakuman so far has been Nakai, and that hasn't been a huge loss. He was kind of a jerk and a creep, in the end, even if he was a good artist.
And on that note, I'd like to say that, although it has thus far been an overall better series than Death Note, I think even Bakuman has had it's share of hiccups.
First is Nakai. I think we all liked Nakai at first. He had this whole loser with a heart of gold thing going for him, and although I don't think any of us really believed he would end up with Aoki, we couldn't help but root for the guy. But then during his "grand exit" he turns into this creep who tries to extort romantic favors out of her. I didn't appreciate that.
Also, I really don't like how they handled the Mashiro in the hospital arc. Everything about that arc was just really weird for me. I know they were trying to show how dedicated to manga he was, but to me it just seemed like he was obsessed more than anything. Not that it was a bad idea for a story arc, but I think it could've been executed better.
And of course there's Azuki. Now, Azuki I'm still kind of iffy about, but it's still enough that it's a detriment to the manga for me. From what we've seen of her she seems like a likeable character, but that's just it; we don't see her that much. I know she's supposed to be Mashiro's goal, the girl he's going to marry after they make a hit manga, but sometimes I'm left wondering why I should care.
So yeah, Bakuman certainly isn't perfect, but then again no series is.