Here's the airbus side:
MEL:
.....
One or both may be inoperative provided:
1) the inoperative reverser is deactivated and secured in the stowed position, and no operation or procedure is predicated on thrust reverse use,....
Crew Operating Procedure:
....
At landing:
It is recommended not to select reverse thrust on the AFFECTED engine......
No further restrictions to be found.
The only restriction on assymetric reverse thrust I could find was the following (all in one engine out ops, which can be compared for aircraft handling purposes)
LANDING ONE ENGINE OUT
A321 ONLY: For automatic rollout the use of remaining thrust reverser is limited to IDLE REVERSE.
So basically, operating under normal conditions, I am only performace restricted in cases that require reverse thrust.
Considering aircraft handling, the FCOM simply states:
-Initially apply idle reverse
-Depending on situation and runway conditions increase reverse stepwise.
I have personally experienced a landing where one reverser failed to open, and had absolutely no problems in directional control. So cases with the limitation already known should be even easier to handle, as the slight yaw moment doesn't take you by surprise.