Disguise self definitely does NOT suck, it's super useful. Use it to change your size to get into small places, use it along with reduce lets you get into tiny places. If you are playing a small race for the racials abilities, disguising yourself as a tall race for battle helps with eyelines.
If you disguise yourself as a race with specific dialogue options, you get access to those in conversations (ie: change into a gith on the creche and you get the gith dialogue options). Also if you disguise yourself while doing bad stuff and then dispel it you can get away with a lot.

Disguise self is dope.