Good ventilation is key for a bike jacket. Also a visible color and reflectors.

I have a Novara bike jacket from REI with removable sleeves. I have never taken the sleeves off, and find they are a pain because they are always coming half unzipped (a little is ok for ventilation, but not to the point where they are ready to fall off.

If it is raining, I'll want the sleeves.
If it is cold, I'll want the sleeves.
If it is warm and dry, the coat stays home.
I just can't think of when I'd want to wear it as a vest.
Perhaps a safety visibility vest, but then maybe I should just buy a good visibility vest and keep the jacket for the rain.

The zipper on the Novara also just seems a bit flimsy, and I'll occasionally miss getting it engaged properly.

My other jacket is an old Burley. It is definitely getting a bit old, but is better made, with better zippers.

Showers Pass is supposed to have Burley-Style jackets. I haven't tried one yet, but it is definitely worth considering.