The book was initially intended to be a serious travel guide,[2] with accounts of local history along the route, but the humorous elements took over to the point where the serious and somewhat sentimental passages seem a distraction to the comic novel.

However, he frequently digresses into humorous anecdotes that range from the unreliability of barometers for weather forecasting to the difficulties encountered when learning to play the Scottish bagpipes.

The book includes classic comedy set pieces, such as the Plaster of Paris trout in chapter 17, and the "Irish stew" in chapter 14 – made by mixing most of the leftovers in the party's food hamper: I forget the other ingredients, but I know nothing was wasted; and I remember that, towards the end, Montmorency, who had evinced great interest in the proceedings throughout, strolled away with an earnest and thoughtful air, reappearing, a few minutes afterwards, with a dead water-rat in his mouth, which he evidently wished to present as his contribution to the dinner; whether in a sarcastic spirit, or with a genuine desire to assist, I cannot say.We had a discussion as to whether the rat should go in or not.

… The Standard spoke of me as a menace to English letters; and The Morning Post as an example of the sad results to be expected from the over-education of the lower orders.

The use of slang was condemned as "vulgar" and the book was derided as written to appeal to "'Arrys and 'Arriets" – then common sneering terms for working-class Londoners who dropped their Hs when speaking.

[4] Modern commentators have praised the humour, but criticised the book's unevenness, as the humorous sections are interspersed with more serious passages written in a sentimental, sometimes purple, style.

[13][14][15][Note 4] Audiobooks of the book have been released many times, with different narrators, including Sir Timothy Ackroyd (2013), Hugh Laurie (1999), Nigel Planer (1999), Martin Jarvis (2005) and Steven Crossley (2011).

The BBC has broadcast on radio a number of dramatisations of the story, including a musical version in 1962 starring Kenneth Horne, Leslie Phillips and Hubert Gregg, a three-episode version in 1984 with Jeremy Nicholas playing all of the characters and a two-part adaptation for Classic Serial in 2013 with Hugh Dennis, Steve Punt and Julian Rhind-Tutt.

In 2005 the comedians Griff Rhys Jones, Dara Ó Briain, and Rory McGrath embarked on a recreation of the novel for what was to become a regular yearly BBC TV series, Three Men in a Boat.

Psmith's boss, while delivering a political speech, pretends to have personally experienced a succession of men claiming to have caught a fake trout.

"[26] Three Men in a Boat is referenced in the 1956 parody novel on mountaineering, The Ascent of Rum Doodle, where the head porter Bing is said to spend "much of his leisure immersed in a Yogistani translation of it.

"[27] In Have Space Suit—Will Travel, by Robert A. Heinlein (1958), the main character's father is an obsessive fan of the book, and spends much of his spare time repeatedly re-reading it.

[28] The book Three Men (Not) in a Boat: and Most of the Time Without a Dog (1983, republished 2011) by Timothy Finn is a loosely related novel about a walking trip.

[citation needed] A re-creation in 1993 by poet Kim Taplin and companions resulted in the travelogue Three Women in a Boat.

[citation needed] Science fiction author Connie Willis paid tribute to Jerome's novel in her own 1997 Hugo Award–winning book To Say Nothing of the Dog.

Her time-travelling protagonist also takes an ill-fated voyage on the Thames with two humans and a dog as companions, and encounters George, Harris, 'J' and Montmorency.