I've tried this a few times now and I just love it! My hair becomes SO soft all the way down to the ends and it stays that way much longer than usually. My hair is always very soft the first day after washing but then the ends starts to get dry and with that loose their softness. With pre-wash oiling it lasts at least two full days before the ends starts to be dry.
The only problem with this method is that it needs to be done over night to really work and I usually wash my hair in the evening.