If I may offer my opinion...
I disagree with the people who are saying they feel the album is "overproduced." That's a word that gets thrown around frequently (not here, necessarily; I'm too new to the forum to know that--but online in general), usually to connote "overly polished." Those are two different things.
If anything, my issue with SoI was that it was somewhat under-produced. For example, Every Breaking Wave, Volcano and California sound quite thin production-wise. On these particular tracks, it feels like U2 tried to get back to a real "band" sound. Many songs feature what sounds like one guitar, bass, drums and maybe a keyboard part or two plus a couple of tracks of vocals. That should be exciting; I know a lot of former fans who have been clamoring for this for well over a decade now. Instead, though, the record sounds a little flat and uninspired, partly because slick production doesn't necessarily complement a minimalist approach. The reason U2's 80s and 90s records worked so well is that the production helped to make mountains out of molehills. The Joshua Tree, for example, is a pretty sparse record, but the way it was tracked and mixed really benefited it in that every single element seems to exist to bolster the next. Mostly it was smooth, but some rough edges were allowed to remain. And as Bono put it at the time, U2 was very much a four-legged table. Everyone's contributions were meaningful.
But the last few records, and SoI in particular, seem to suffer from a situation where U2 as a band and their production team(s) simply show up to lay down songs, but nobody is overly concerned with making them sonically interesting. I can't speak for everyone, but I feel that oftentimes, our favorite records resonate with us deeply because the production matches the material. U2's rhythm section, being solid and workmanlike but never particularly elaborate, doesn't benefit from a boring-assed OneRepublic-style sheen. It just flattens out their dynamics, which is part of what makes them a unique band.
If the band are going to split up production duties among 2 to 5 hired guns anyway, then perhaps they should hire the best person for each job. For example having say.. Butch Vig produce the rhythm section--or maybe the entire song, in the case of an uptempo rocker--would certainly lend some girth and liveliness to that side of the material, which would (one hopes) force Edge, Bono, and whatever producer(s) they opted to bring in to dig deeper and push harder to really deliver the goods on whatever vibe they're trying to conjure. Hell, record Larry and Adam to tape. Get great, one-take live performances, and don't edit them any more than is necessary. Take risks again.
I really think what this band needs to do is to just indulge their own instincts and not worry about what's happening in the pop charts. It's okay that they let the broader culture influence what they're doing, but it shouldn't be the ultimate decider. Trying to write a hit record as a 45+ year-old white dude is, at this point in history, a fool's errand. They are inherently unable to access the heart of the present youth culture, and that's as it should be. That's not to say they couldn't have another big hit, but it seems to me that it's far more likely to occur with recorded material that sounds like everyone is invested and committed to it, as opposed to material that merely sounds competently designed to compete in today's marketplace.
TL;DR: I actually do like SoI. I just think it would have been better if it had been produced creatively instead of effectively.
I find this comment bang on, particularly the point highlighting how SOI proves that slick production doesn't compliment a minimalist approach, which is what makes songs like Every Breaking Wave, California and Volcano, feel kind of flat and uninspired because it felt like the band were going for a 4 people playing in a room approach but they then proceed to put so much effort into polishing up the final mix and ironing out the kinks and rough-edges that you have this sort of division where the production is in contradiction with the feel U2 were going for in the first place!
I would prefer that these songs were made in the way that U2 did in the 90's, when they had the approach to create more-from-less. They laid down the foundations of the song, kept the raw and organic sound from what they recorded and then added all the additional effects later on.
(instead of putting lot's effort into trying to polish up the rough edges and making the final mix sound as clean as possible)
"The reason U2's 80s and 90s records worked so well is that the production helped to make mountains out of molehills."
I like that full, luscious production from tracks from 'POP' such as Do You Feel Loved, Discoteque, Mofo, where the production is dense and full but the sound isn't smoothened-out and polished to feel more comfortable for the ears and that rawness isn't ironed-out - in contrast to what we got with many songs on SOI such as EBW, Volcano, California etc..