My hands were shaking during the last boss, but I actually think it's much easier than the previous boss.
If I had to rank the bosses in order of difficulty:
4. Supreme AI (6)
Similar to boss 4, with a little more to account for. Still, the area between lines of bullets gives you a decent amount of space.
6. The Architect (5)
Phase 3 just throws everything at you in a small space. It's chaos. Between the fanning bullets, standard lasers, deadly purple laser, and the occassional enemies, you're pretty much guaranteed to die, and once you start dying, you'll keep dying until you kill him. I just watched Jimmyqballs run on youtube, and even he fared about the same, so I don't feel so bad.
Such a great game!
Not sure where I go from here. Master is probably insane. Or maybe I try to beat the final boss on Experienced.