It's amazing how repetitive the monster manual gets after a while. Case in point: the wraith, which is basically the same as the shadow and spectre, just in-between the two in terms of power. Ah well, at least it makes comparing them easy.
The racial features aren't surprising. 5 RHD Undead with the incorporeal subtype, a touch attack that deals ability damage (constitution this time), good bonuses to what ability scores they do have, spawn creation, and turn resistance. Alertness and Improved Initiative as bonus feats are unique to this monster, and moderately useful.
Unnatural Aura is annoying in a handful of cases, valuable in some others, and in general not worth mentioning. Daylight Powerlessness is a non-insignificant weakness (I assume it functions the same as the spectre's Sunlight Powerlessness), and constitutes somewhat of a reduction in overall playability.
Compared to the spectre, the wraith has a better touch attack and free bonus feats, but the spectre has superior spawn creation and movement. In the end, I think a LA of +2* is justificable here: it allows shadows, spectres, and wraiths to all possess their own strengths and weaknesses, and makes each of them a viable option.
I stopped reading after seeing the RHD amount. I don't care these things are as dextrous as huge air elementals, dread wraiths are never going to catch up with their class level-enhanced lesser brethren, let alone humanoid PCs. -0* LA.