The i432 was well before my time, so it's hard to account for the privilege of hindsight, but I found myself looking in horror at most of its design. Hardware needs to account for the fact it's ultimately a piece of physics, and the i432 dismissed this completely.
It's a real shame because the failure of old innovative architectures—faults ultimately down to poor and complex designs—have burned people enough that few people dare to try again. For all its flaws and forever-vaporware status, the Mill shows that you can make an architecture much safer without paying extra as long as you do things with principle.