It seems like the complaint is only about the adept edge, not the master. I have no clue about any of this of course, but I assume you need to take Adept to take Master though, and master looks really nice, so I would see it as probably worth taking adept just to take master.

Spectral Adept says in the form of a wraith to greater effect. Does it grant any additional neg, poison, disease or cold resistance, as opposed to general DR? These do not always show in the damage screen, but testing should bear it out, and I do think Torak is usually pretty thorough in his testing of things, so this is probably not it. More like a wraith would be more like an undead, though I am probably missing some other beneficial wraith aspect that Ish was hinting at. Less hunger, thirst, better mana or health regen, spellcraft bonus, who knows.

Master looks pretty sweet to me though, giving dodges, stronger damage and mana draining to translucent foes, which are most mages.