I'm reserving judgement until we see a high level PC.
Reason why I say this is because the 3E PHANE at first glance, looks very impressive.
Check it out, in the SRD and I was really jazzed up about DMing it.
The reality? Perfect example of why High-Level just plain sucked. If the PCs were prepared for it, they could kill it in one round without any trouble. If the PCs couldn't kill it in one round, they certainly would finish it off in the next.
Conversely, if the PCs weren't optimized/prepared, the Phane would kill a PC every round and you end up with a TPK in short order.
There was NO middle ground, you didn't get actual rounds but worse, the actual time it took for the battle was so unsatisfying. The pre-battle plan would take almost 30 minutes which would result in a 45 minute one round encounter.
As a DM, high level was all types of FAIL,
To those that want a complicated monster, you can have the 3E Phane. I just can't imagine said people actually being DMs given what tended to happen with "complex" monsters.
Seriously, to the people decrying the simpler monsters, have you EVER actually DM one of the more statblock heavy creatures at hgih levels?