[5] Affinity was the first time that all six members of the band contributed with compositions from scratch instead of building music around the guitarist and keyboard player Richard Henshall's ideas.

For instance, Charlie had some really cool stereo guitar lines for the middle section, I came and added big ambient/electronica/sound design textures to it, then Conner [Green] came with an incredible bass solo.

[11] In a review for AllMusic, Thom Jurek compared it to the band's previous work by clarifying that it's "less dense than The Mountain musically, but no less sophisticated.

The striking harmonic sensibilities in these songs are marked statements of how prog is capable of attracting those listeners who aren't predisposed to it, but more than that, it's great fun to play.

"[8] Writing for Sputnikmusic, Thompson D. Gerhart praised the album but was not as impressed as he was with The Mountain, stating that "while the group execute with precision on the dystopian, hacker-y concept dreamed up for Affinity, the broader space for dreaming on The Mountain seems to have allowed for more big and sprawling ideas to come forth and flourish, while it's the quick hits that deliver the statement of Affinity most articulately".

[15] The Ultimate Guitar Archive team praised Haken's songwriting and the unity among members, but called Jennings's vocal work "restricted" for relying too much on his head voice.

[17] All tracks are written by Richard Henshall, Ross Jennings, Conner Green, Raymond Hearne, Charlie Griffiths and Diego Tejeida