For exposure compensation in manual with auto ISO: for cameras above the base level, at least, exposure compensation still works in this mode. If you exposure compensate, the meter adjusts how much it changes ISO. The main issue here is that if the ISO you're starting with is already at one or the other extreme, the compensation cannot exceed it. So for example if your settings cause the auto ISO to go to 200, you cannot compensate in the minus direction more than one stop on a camera that bottoms out at 100. The compensation will not touch the manual settings. But if your auto ISO lands you in a more middling range, compensation will adjust ISO as expected.
This is not the case on low end cameras with only one selection dial. On those, one cannot exposure compensate with Auto ISO because the compensation button is used to switch the dial from shutter speed to aperture.
As Ann notes, if you do panos, make sure any auto exposure, including Auto ISO, is off. I, of course have never done this never admitted to this.
