It's totally exploitable. You can watch few last Thorsten77's videos, he explains it well.
Limping from ep is wrong, because you have to fold to a raise which is very likely to happen.
Limping from mp is wrong, because you have to fold to a raise which is likely to happen. (it's ok if there are few limpers before you)
Limping from lp is ok if there are limpers in the pot.
But don't forget to fold to any raise and do not call anything bigger than one big blind.
And it's exploitable, so I don't really like it... but well, it's playable the way I explained it.