My transaction was smooth, albeit switching back and forth between u2.com and ticketek sites. Had a look at P2 tix for Sydney, but they were almost in the far corner, so had to start again and got P1 on side of stage (section 105). No probs with codes and still have one left.
Tix are expensive but that is the market, and still much better value than Coldplay GA at $200+.
Would have been much easier and less stressful if (1) email was sent earlier and had explicit instructions and (2) a seating plan was available. How hard can that be, either stadium or ticketek at fault. Imagine the chaos if no seating plan when general sale starts!