Not sure what was bad about the DOS and Windows compatibility? OS/2 was frequently touted as "better DOS than DOS, better Windows than Windows" and it was generally true. You could multitask DOS apps (lots of people used this for running multi-line BBSes and so forth) and Win16 apps could crash without bringing down the whole system.

Of course OS/2 was later severely hampered by its inability to run Win32 apps, but that's another story.