It was impossible to read every post of the thread, so I'll give you my view even if it may repeat someone else's...
First of all, the artwork rocks. And that wouldn't be so important if not because it characterizes the creature much better than before, allowing DMs to customize it, describe it the way they want, but staying in the theme of such a nightmarish, weird, and suggestive creature.
Then I would like to point you to the tactics section and to the Phane's speed, that the tactics mention. 10 is VERY much. And shifting FOUR squares each time you attack as a standard action with the touch which has range 2, means that the Phane can really make effective "flyby" attacks, even on the ground.
Speaking of its powers, the
slow effect of the touch appears to be NOT SAVABLE. You are slowed and you must deal with it. So that's another difficulty when you're actually trying to BEAT this guy. You may not be able to approach it.
Wizening Tempest is also more wicked than it first seems: the stun effect endures AT LEAST one round. And after that the after effect makes you BOTH dazed AND weakened.
Last but not least, as many already said, the ability to shun ongoing effects and to be insubstantial (note that all the other examples of creatures using "insubstantial" couldn't attack while insubstantial...).
I must say that I discovered these details only the second or maybe third time I looked through the stats and the whole page. They are straightforward, the 4e monsters, but only AFTER you understand them thoroughly. And even if it doesn't take much to understand them, ALL the examples I've seen took quite a bit "cpu cycles" to understand them...
The good thing is that once you understand them, it's like when you master a modern videogame... You can do all sort of badass things with them without even thinking!
We just have to get used to some new "joypad buttons" like

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