I'm not sure it's a great example really for the very reasons you're saying - it's hard to say what's real and what's not but it's one of those shots that screams CGI because it's there to impress with scale, therefore the fact it's a composite is quite glaring. There's no issue over the quality of the CGI or composition, but the way the scene has been chosen to be shot adds to a sense of unreality. It's a problem of sci fi and fantasy, the temptation is to go for the wow factor.
However, If CGI was used in the battles in Kingdom of Heaven, which I assume it was, it's been shot in a much more old school 'David Lean' epic sort of way: not adding extra disassociation with lots of flying camera moves.
I'm not too worried about Ridley Scott employing CGI, he isn't going to carefully craft and light a film only for the FX to scupper a sense of reality. He decided not to have a CGI rhino fight in Gladiator, and has preferred to use sets and practical FX augmented by CGI in the last decade.
Look at the trouble they went to with the final cut of Blade Runner, bringing back Joanna Cassidy and Harrison Ford's son to fix shots rather than just rely on CGI. Ridley knows how to use the tools of the filmmaking trade to the best advantage.