horatio, come blow your horn
Forester is best known as the author of the Horatio Hornblower novels; Hornblower has been the quintessential literary naval officer for decades, though's Jack Aubrey is catching up to him. Somehow I had avoided reading any of the Hornblower novels until recently, so I've come to them after Patrick O'Brian; this is not the typical order, and so my opinion is perhaps biased.
That said, I've enjoyed the Hornblower novels I've read so far. They haven't the depth of the Jack Aubrey novels, and indeed I think O'Brian excels Forester in almost every way, but they are likely more accessible as well. Indeed, I think I'd have appreciated O'Brian's work even more had I read Hornblower first, to acquaint me with the milieu: the Royal Navy in the Age of Sail, and more particularly during the Napoleonic wars.
The Hornblower novels were not written in chronological order; rather, Forester wrote a couple of novels about the moody, insecure (but amazingly competent) captain, found them popular, and then filled in the rest of his career. This leads to some obvious inconsistencies; the step from Hornblower and the Atropos to Beat to Quarters is particularly jarring.
I don't wish to be too critical, however; many of the books have been a genuine treat.