I used it when I was SENCO in a primary school. I found it really useful as a way of supporting staff go get going wtih writing IEPs. The school had a very low level of understanding about appropriate targets, strategies and achievement criteria, so IEP writer gave them a starting point. It gives a wide range of suggested targets in different areas, but it's really important to personalise it as some of the achievement criteria are a bit dodgy.
So on the whole, I'd say yes, we found it good. I did find that I needed to spend a lot of time supporting staff initially as they weren't used to writing their own IEPs at all, let alone using a software package.