1) Shifters as relatively non-gear-dependent for many purposes. I.e. you'd probably rather have a shifter groupmate with no gear than a warrior groupmate with no gear.

2) Shifters as not/less bothered by many things that are hard on other magi. E.g. deafen, tiger claw, gag, manacles...

3) Unique difficulties of in-form communication.

4) Spells are cast as a human(oid)... so you've got your I can use utility stuff and my spells more, and your I'm shifted and down to business mode.

5) Some shifters (defense in particular) as great for group-based exploration of really high-end areas.

6) Maybe some rough explanation of the "extreme" nature of off/def foci. I.e., you could build the most pure-offense warrior you could, and that guy still almost certainly tanks better than lion. You can build the most pure-defense warrior you could, and that guy still throws more damage than anaconda. Plays to a bit of a different style than warrior.

7) Shifter as generally good at dealing/avoiding damage but often lacking in maledictive / command denial power?

8) Shifters as differently-bothered by things that hinder other meleeish characters. I.e., lions don't have wrists and can't drop weapons. Maybe also mention of shifting trauma.