+ 1 on confirm before attribute point assignment.
+ 1 on respec method that ernzor mentioned.
I'd also love a way to "play" with my next level point assignment and respec before actually deciding.
Had two ideas:
1) Use the arena as a way to test out your skills if you were at the next level. Give option to assign the additional 6 attribute points and 1 talent point temporarily while in the arena. The points would be removed after leaving. Could be a incentive for folks to frequent the arenas more?
2) Have a training ground that lets you respec upon entry with either the cost of resetting your respec cooldown or low EP cost (say 50EP). The training ground could be a small open-world area and have some monster spawn + PVP. The training ground would have no exp and no durability loss. If you like the "educated" respec you could then keep it for the full EP cost or cancel and just loose your cooldown/50EP.
Dunno... just thinking of more creative ways to test and refine builds besides full respec. Path of Exile's leveling leagues are pretty cool too.