I know what you mean...its a big brush and it will need quite a lot of soap and you will have to adjust your technique, just make sure you use enough, in fact use more soap than you think you need and I think you will find it lather's more than adequately.
It took me quite a while to get used to it, I do like to start soaking mine with the hottest water possible for the duration of a 10 - 15 minute shower. The trickiest part to using this brush though is knowing how much water to leave in it. Because of the nature of the hair it's really easy to squeeze this brush too dry even when it come's to loading it with soap, there is a fine balance to be had especially if you are only face lathering.
After the first pass and having built lather on the face and in the brush, for subsequent passes mix up your'e lathering technique a little by using some painting strokes.This tends to brings the hair back together again, I personally don't use "rotary" lathering technique for applying lather for subsequent passes as I find it's counter productive, the lather is in the brush, I did my bit of rotary exfoliating and agitating for building lather now I just keep it warm and paint it on for subsequent passes. I do this with all my brushes but especially the larger ones.