That's gigant, not giant.
I'll be blunt: 32 construct HD shatter all hopes of this being remotely playable. The terrible stats (aside from 45 strength everything is 10 or lower) just add insult to injury. A few random resistances, fly speed, and SR don't make up for the fact that, well, you're using this when everybody else has 12 Epic levels already.
That said, the blackstone gigant sure gets style points. Its main natural attacks are a quartet of slams that all force a save versus petrification. It can give up on a single slam attack to animate a creature turned to stone this way, which is mostly useless against adventurers but is incredibly cool and should honestly exist on some lower-level monster.
Interestingly, the alignment section mentions both that it's 'same as creator' and 'usually neutral evil', despite no alignment restrictions existing for the creator or necessary spells. Apparently evil casters are just more likely to waste resources on a giant stone monster.
With all that said, blackstone gigant bad as a PC, relatively poor as a monster, amazing as a concept. -0 LA.