This is one of the better Conan stories, with a cannibal cult, a magician, a strangler-killer and a topless damsel in distress. All one needs for an adventure.

Top literature. Much better than the more famous King Arthur. Orlando and the peers of Charlemagne is a truly epic work which should be more known in the English speaking world. (Translated from Italian).

REH's attempt at writing a Fu Manchu, yellow peril adventure (although the title villain is actually Egyptian), is serviceble enough, but Howard was never his best when he tried to imitate his contemporaries. It's a decent if unmemorable read. You can find better REH on this site.
And the usual blah, blah, blah, complaints about racism whenever the villain isn't German.

This is the first piece of fiction I've found on this obscure conflict, the Russo-Japanese war. It involves an unnamed American-Polish spy working for the UK and as a double agent for both the Russian Czar and the Japanese Mikado. It involves spy ships, trans-siberian railway and beautiful, seductive princesses.
It does have an annoying characteristic of not fully naming characters, calling them Princes Y____ and Prince Z____.

A spy novel set during WWI, but really more of a look at upper-class, rural British society. The mystery is fairly interesting.

I was curious to see how Henty would handle a female protagonist, since all of his male protagonist are exactly the same character. Well, he just turns the plucky English girl into a plucky English boy. She even shaves her head and dresses up as soldier.

A nice lost world style adventure. generally a fun read but its been done so many times since it loses impact. I would have liked a female character to be on the adventure.
Personally, I prefer the Professor Challenger stories.

Like all Henty books, this has 3 major sins. It is long, it is boring and it is chauvanistic (in the original sense of the word). Honestly, how do you make a book about King Richard in the crusades somehow longwinded and boring? He can do it. And King Richard (who spent so little time in England that he didn't even know how to speak English) is your patriotic English hero, according to Henty.

Not a bad book at all. A young Roman aristocrat is forced by court intrigues to go on the run, including time as a disguised slave. It pulls few punches, not idolizing the time period, the high Roman empire, nor condeming it. Of particular interest are the passage on Emperor Commodus, his skill at chariot racing and fighting in the Coloseum. He is not presented as a fop but an accomplished athlete. Worth your time if you like old Rome.

Almost no detail about the time period, almost no action, a prototypical Henty book if there ever was one. Read only if you are a masochist like me.