I went back and forth on this a lot before deciding not to vote, because a)I don't know and b)I suspect the real answer is somewhere in between "lying" and "not lying" (in particular, I imagine motivated reasoning played a large role). It would be interesting to read Bush's memoir sometime to see what he has to say, but I imagine that actually reading Decision Points would get pretty tedious. I will say that, from what I remember reading and from reading a Wikipedia article (
https://en.wikipedia.org/wiki/Iraq_and_weapons_of_mass_destruction) to refresh my memory, it does seem like the invasion of Iraq may have taken out a regime that was deadset on acquiring WMD's, even if it didn't already have them.
Anyway, at the end of the day, the Bush Administration botching the war matters a lot more than whether or not they lied.