The Cruel Sea (1953)
Is a much better film about this particular time in history. It feels better paced perhaps because it covers the while period of the war so doesn't have to maintain the level of intensity this film attempts with it's story of a single convoy.
I though Greyhound was OK overall - it exceeded my low expectations anyway. I found the sound track intrusive and inappropriate, and the CGI was excessive.
I'm wondering if they could model the look of a film like this on the films of the 1940s and 50s and stop trying to produce panoramic CGI seascapes and not very believable almost collisions and similar close encounters all the time. Or maybe that would be deemed too old fashioned an approach these days?