The key point to aura masking is in the first sentence of the power, and later on the write up:
You learn to change the appearance of
your aura (and astral form). You can make it look mundane,
or make your Magic Rating look higher or lower
by up to your grade. When someone tries to read
your masked aura, the Assensing Test becomes opposed
by your Magic + initiate grade—if they get any
net hits, they see both your mask and your real aura.
If you can use astral perception, you can even make
your aura look like a different type (like a spirit or a
focus—great for astral costume parties).
THIS is key!
Normally, the singular way to tell the difference between "Us" and "Them" (the uninvested and invested) is their aura. But you have the ability to hide your investment, and thus your nature by making your aura seem to be that of something else entirely.... SO you are
not an invested elf, but merely an awakened elf...
you ARE the Wolf in sheep's clothing.
So lets look break this down from your character:
For 42 Karma you got:
Aura masking to hide your true nature (and stop you from getting geeked on the first astral perception you run across, but may not hold up to a dedicated look, true)
Realistic Form (again so you can hide your true nature as a spirit, and as a consequence of your investment)
Enhanced Smell and Thermo vision (smell, while disgusting, shouldn't be overlooked! and vision in total darkness... very handy)
Immunity to normal weapons (nothing like 12 free points of armor with 6 auto successes for damage resistance! Enough said

)
Venom attack
Binding (not as in spirits mind you, but as in "I stop you from moving by throwing webbing at you, spider-man style)
Wall crawling. (great, now I have to worry about you blasting me from the ceiling?!!? Fuck.)
And you get very sick around a can of RAID!... ok....
Everything else an other adept could get so I am not worried about it in the least.
However, don't forget that as you progress, you can pick up any one of the these CRITTER powers (they work a little differently then spells in some cases) for just 9 karma at a rate of 1 for every 3 points of magic:
Animal Control (Insect Type), Compulsion, Confusion, Enhanced Senses (Ultrasound), Fear, Search.
Again, those are some great abilities to have the option to take for a low cost which are not tide to your power points. (even if they cost more karma to get).
Now, don't get me wrong, I am not saying you shouldn't run a specialized game with this character (in fact I think that is a far better option than trying to drop an Insect Spirit Player into a regular game). Just saying you want to keep your eyes open to the power level and the abuse that this concept brings with it so you are better prepared for it and it doesn't derail a game session through an unnoticed flaw!
For example, basing the game around an opposition of a bunch of street toughs with no magic support and the best weapon they have are light pistols may not be the best mission concept when a player has 12 points of hardened armor.
Again, I'm not saying you shouldn't. Just that you should, with eyes wide open.