Writing in Smash Hits in 1979, Red Starr said the album was an "intriguing but only occasionally attractive array of verbal and musical images". Starr went on to say that it sounded like "pointless backroom self indulgence".[7] Steven Grant echoed Starr's ambivalence in Trouser Press, saying that the album "has an obsessive strength — like Eno in his stranger moments but without his repetitiveness," but that "The music, though fascinating, is rarely coherent."[9]
In a retrospective review, Head Heritage described Mix-Up as "a great snapshot of a brief period in post-punk UK when there was a sudden urge to grapple with a bizarre, homemade, hamfisted white dub landscape."[11]AllMusic writer Andy Kellman was less favourable, writing that "Cabaret Voltaire's first two proper studio albums hardly match the greatness of later works like Red Mecca, 2 X 45 and even 3 Crepuscule Tracks", while noting that Mix-Up "only helped solidify Cabaret Voltaire's status as an integral part of the extended frisson of 1978–1982 post-punk".[1]