I'm seeing two consistent issues with the process replays(ES2 SP2).
One is that workbench completely crashes when I replay a specific process. A workaround that I've found for this is to open the process first in the editor and then select a process instance to replay.
The second issue is that I can't delete process recordings. When I pick the delete recordings option, no process instances appear in the list. I can replay the recordings, though, so I know there are several.
Here is another one. I'll replay a process instance. It will start fine, but after a few process activities, the replay window will freeze, but the progress bar at the top will continue. I have to close the workbench completely and reopen it to continue with anything.