The album also shows a shift from Harris' usual nu disco-style songs, focusing more on an electro house style.

[17] "Drinking from the Bottle" was released as the album's sixth official single on 27 January 2013, featuring English rapper Tinie Tempah.

[27] Fraser McAlpine of BBC Music hailed the album as a "collection almost exclusively in the key of triumph", as well as "a portfolio of win for Calvin, an annual report where the graph is almost all peaks and the troughs are so far down they're practically invisible.

"[37] Arwa Haider of Metro commented that "18 Months could be a capsule collection of smash singles, yet it also works brilliantly as an album.

[33] AllMusic's Tim Sendra wrote that the album "shows Harris to be a solid producer with an easily identifiable sound.

"[32] The Independent's Andy Gill was unimpressed by Ellie Goulding's performance on "I Need Your Love", but complimented Welch on "Sweet Nothing", and cited Harris's collaboration with Nicky Romero on "Iron" as the album's "killer cut".

[31] Emily Mackay of NME opined that "[t]he best collaborations stand alone, but the rest demands small hours and sweat to animate it", stating the album "feels more like a deserved victory lap than a forward step or a new instalment, but apart from his sole vocal on 'Feel So Close', the victor seems oddly absent.

"[34] Killian Fox of The Observer remarked, "Nothing else on 18 Months matches up to the blockbusting collaborations with Kelis, Florence Welch and Rihanna", concluding that "Harris's production has become increasingly homogenised and, despite the array of vocalists, everything here risks sounding the same.

Club's Chris DeVille felt that the album "suffers from EDM fatigue" and that "almost every track eventually congeals into the same automaton thud.

"[29] Evan Sawdey of PopMatters critiqued that "while 18 Months [...] is pretty much the hit-making monster that launched [Harris] in to the world spotlight, the truth of the matter is that it feels like a rather compromised vision of who he is an artist, sacrificing his quirkiness for a brooding new persona that starts to get stale over the course of a complete full-length.

"[36] The Guardian critic Rebecca Nicholson expressed that "Harris knows how to make the most of his guests, leading them through a series of euphoric bangers that seem destined for success.

But for all the pop divas he has roped in, there's a veneer of cynical, laddy EDM, resulting in the kind of tracks Skrillex might come up with on an Ayia Napa booze cruise.