tbh no as its a build up weapon. also in other games once you freeze an enemy you cant do anything to them till they defrost. a slow would be nice but again before the beam reaches full power the enemy youre fighting is dead. the slow should start from get go if they were to add one.
In the games I've played you kill them in one hit because they're frozen and the ice breaks :S Even if it just froze the enemy like that I think it would come in handy in certain scenarios. Not to mention it's just an idea that I hope Bungie would consider and build upon themselves so that it works. It adds variety. Warframe does it and it works beautifully. If you freeze an enemy they're no different to being unfrozen, it's just they can't move... You still kill them with the same DPS you normally would have.