Unfortunately it depends on situation, Got one for my DREDD loadout and decided to bring it along to a skirmish, while my pistol was going it was a simple if you get shot your out and you drop the shield for whoever comes along.
And then my pistol packed up so it was allowed for me to keep hold of it the whole as long as I used my "daystick", great fun for everyone, me included, quite proud when I was able to get 5 of them in a row (see below)
It is really a case of how they are used, can be great fun, but if there are no flanking opportunities or capable of overcoming, it can suck big time.