It is a good dlc to Spellforce 2, not great but good. It isn't so short - it takes me 18 hours to finished it what was longer than many dlc's to new games. The storyline is not bad, characters are quite good - the real trouble with them are sometimes embarrasing dialogue lines which don't exacly suit same npc (Caine for example).
Graphic remember time of Spellforce 2 which isn't great, music on the other hand is fine.
Of course dlc is far away from greatness of Dragon Storm but that's propably is caused by changing of studio. Faith in Destiny is quite challenging - it isn't so easy as it looks, and same storyline have some potential in it, also if somebody wish to play in next dlc ("Demons of the Past") it is good to know Faith in Destiny first - without it you can loose some important information from storyline.
I can advice this dlc to everyone who loved Spellforce serie - Faith in Destiny represents almost all what was good in this serie - even if it doesn't add anything new (besides new kind of enemy) to it but it's a very good reminder.