Well, perhaps "weaknesses" isn't the best word to use, but what I was referring to were mainly the depictions of the Kzinti and the inconsistent "fit" of them into the larger ST universe - the line in the episode about the Kzinti having fought four wars with humanity and having lost them all, their lack of appearances in other ST canon, and such. I know, of course, that the Kzinti were a carryover from the "Known Space" universe, and they don't really neatly fit into the larger ST canon. It seems to me that their purpose in the story could have been served equally well by an Orion pirate crew, or something similar. I know the issue of the Kzinti and their fit into ST in general has been extensively discussed elsewhere, and there are varied opinions on the subject, but that's what I feel about it. Again, perhaps I could have used a different word to describe it but that's what I was referring to.
I see what you mean. The thing is, though, that at the time the episode and its novelization were made, Trek chronology hadn't been firmly defined yet, so those aspects only became problematical later on, once TNG and its successors locked in the chronology and filled in the history. So it's only a weakness in retrospect.
Personally what surprised me is that Foster didn't attempt to reintroduce any of the details from "The Soft Weapon" that Niven had left out of the episode, or at least make a nod toward Niven here and there. He pretty much took his own independent approach to fleshing things out, as if it were any other episode. Of course, I don't know if Foster had even read "The Soft Weapon," but it seems like a reasonable possibility, given that he and Niven were contemporaries in the SF literary community.