I got the DVDs of all eight of the A&E Hornblower movies (1998-2003) for Christmas year before last and the other night decided to watch the two that covered the majority of Lieutenant Hornblower. Not really sure why - I have never liked the book because it was the first one I read (the only one the Pemberton library had in 9th grade) and it bore no relation to the English sea captain that Gene Roddenberry said he based his captain in Star Trek on. It's just not a comfortable book - a mad captain, a tortured crew, a Hornblower that has to lead from behind, and so forth.
As always Ioan Gruffudd is magnificently cast as Hornblower, and has a great cast around him, but as a lifetime fan of the original Forester books, I think I am entitled to say that Paul McGann is too polished and intelligent for Bush (although he's actually my favorite on the series). I like his Bush - a lot - but he's just not the efficient but slightly dim character I got from the books. I might should reread the book, but this book is told from his character's viewpoint, and it might give me a better impression of the McGann Bush. Nicholas Jones is really, really good as the dithering Lieutenant Buckland. It would be a mistake to say he was well-cast because I had no trouble picturing him doing a lot of other roles as well, but I would say that he does a great job getting the essence of Buckland across. You could play that role less dithering, I suppose, but for a TV series, I think he needed to be clearly pegged as someone out of his depth. Not weak precisely, but not capable of leadership.