This seems pretty cool: U2 – A Diary is currently #2 in sales on Amazon UK in the U2 category. That gets updated regularly, so here’s a screenshot in case it changes soon:
Number one is U2 Show, which is on a clearance price of only £5 UKP – no wonder it’s at #1.
I suppose this is all relative. If UK book buyers aren’t buying many U2 titles, this may not indicate good pre-orders whatsoever. But it still looks cool.