The Freelancer is a good addition to every mod or DLC... But.
But it always ****s up your campaign and your end game. Always!
I'll explain. First of all your progression on the global timescale will be slower than if you would play by you own, not as freelancer. The amount of fights which your lord will be able to give you will be low. In the meantime some kingdoms will fall and disappear from the map, lords armies will become bigger and bigger and you will still be noone. Without a money, relationship and other stuff.
Second, is that your companions do not gain levels from this type of gameplay. So, you will have to deal with gimped low level companions after you had enough of serving some lord.
TL;DR: Freelancer is only good for casual short campaigns, which you don't even want to play up to the end.