[1] For the sessions, the band worked with American producer Robert Musso and mixing engineer Terry Date.

[2] In addition to the new songs, Don't Be Happy... Just Worry also features all four tracks from Mondo Akimbo a-Go-Go, newly remixed by Date and dubbed the "Anti-Dance Mixes".

[7] Martin later reviewed the EP for Music Week upon its 1994 reissue, this time awarding it three out of five and hailing it as being "brimful of topping pop rock songs".

[4] In a retrospective review for the website AllMusic, Eduardo Rivadavia gave the EP two and a half out of five stars, describing it as a "much-improved second effort" by the band.

[6] Rivadavia praised the release for "prov[ing] just how far the Wildhearts had come in those six months", highlighting "Splattermania", "Dreaming in A" and "Something Weird (Going on in My Head)".