I completely agree regarding the strength of Iris. Among the strongest tracks U2 have recorded over the last 20 years, quite possibly since the stirring & emotional Mofo - another track over 5:20 in length on the topic of Bono's mother.
Iris (Hold Me Close) is the emotional & spiritual centerpiece of the record & it helps to flawlessly bridge the sides A & B with remarkable effectiveness.
I know some on here aren't particularly huge fans of the record for it's relative 'safeness' but it's such a well-written album. The songwriting is top-notch. I don’t think many bands can release such a good late career album. The only ones I can think of that are better are Clockwork Angels by Rush & Blackstar by David Bowie.
I believe SOI is one of their best albums. Conceptually, lyrically & melodically, it's among their best. It's their tightest, most focused, thematically strong & dynamic set of songs they've put together (at least since Pop/Zooropa).
The disappointment that I felt with each of the 00s albums is in stark contrast to the delight I felt with this record, It is confident, bold, It has a cohesiveness about it and it distills different things I like about U2, lyrically and sonically. Edge laying off the chiming and slide solos that became so boring in the 00's, Bono going a bit deeper and darker with the lyrics and avoiding the clichés of the 00s. The rhythm section sounding urgent again.
Lyrically and sonically, IMO it's their most interesting record since Zooropa/Pop.
For me it's unquestionably superior to ATYCLB, HTDAAB and NLOTH. I return to SOI time again & again. It feels more fully-realized compared to those albums. So while it may not necessarily be U2's finest record since Achtung Baby..(that honor belongs to POP).. it's definitely their most complete, in my opinion.