Pretty much the same pros and cons those races would have if you chose any other class.

Arial: perma-fly. Vuln water/ligthning. Hydrophobia. Can't wear normal boots, normal "about body" gear. Wingsweep inherent.

Half-elf: Half-vuln to iron. Can't wear iron gear. No inherent ability. 24 int, so you get 75% w/ one prac.

Perma-fly is semi-nice as a non-duergar shaman, since it prevents you getting tripped to death by some cheapshot thief. On the other hand, wingsweep isn't so useful since you already get the earthquake commune. You can cover the lightning vuln "semi" easily w/ gear, but not the water vuln. The water vuln's only really a problem when you're fighting invokers, or people with specific weapons. If you're good-aligned, that mostly eliminates one of the drowning weapons (since it's good-only).

If you're half-elf, you might not want to go evil, since there's some good evil gear that's iron. Then again, good-aligned people (who are likely to be your enemies) are less likely to be carrying iron weapons.

The two classes' int stat is approximately equal, so mana regeneration should be approximately equal.

NT