I've hit the 1/5th mark today. Retaining new kanji is beginning to get tougher now; not much, but it's not as easy as the first couple 百。The reason for this is that I still review the ones I've already learned along with the new ones using Reviewing the Kanji. At the moment though, I've done about 1,200 reviews, with a roughly 96% retention rate (not bad in my opinion) overall. I have slacked a bit the last week though, and have only been averaging about 15 a day. I'd rather this be 25 a day (it was 28 yeasterday), so next week I'm stepping it up a bit. I'm more than comfortable with my current rate, so I don't think 25 a day for me will be too fast.
More updates soon!