I actually do understand the Walmart comment -- the album has its "U2 goes a bit arty but not too arty" moment, it's "rocker like Vertigo moment", its "easy pop-tune" moment, etc... In other words, it's calculated (as any album that's three-years in the making with Eno on board is bound to be) -- this is something you didn't feel listening to their music in the 80s and early 90s.
As for the comments that U2 do "subtle" better than "over the top"... Ba-Ha-Ha-Ha-Ha....!
U2 has always been, and will always be, masters of larger-than-life, lack-of-subtlety, aim for the jugular, hit-you-over-the-head, in your face, music and themes. This is the one thing the band has always been known for. It's also something they do well (unlike, say, hair-metal bands of the 80s!).
Anyway, my beef with NLOTH is not the Walmart or the subtlety aspects, but rather that I think the songs are a bit sub-par. I don't foresee many of them surviving in the live set for long, for example.