There's so much bad to say. They "upgrade" the system several times a year, which results in complete overhauls in the way the system works and looks. This is a classic example of developers making changes simply to justify their jobs. With each "upgrade" there are more and more features that have absolutely nothing to do with any "normal" immigration practice, and they have recently starting requiring you to complete forms in certain ways, whether these are truly required by USCIS or not. (Example: they dictate that you use mm/dd/yyyy format even in fields that USCIS couldn't care less about - you can't save the data unless you use INSZoom's dictated format.)
Their support has improved a lot over the years, but that isn't saying a lot. You can now speak to someone who speaks intelligible English, at least. Instead of addressing your concern, they feel they have to call and site your computer, even if you have a very quick question.
I could go on and on with the frustrations I have over this software program. But the main problems are to do with their over-development and over-complication of something that could be much simpler. All I can say is BEWARE. I don't know anyone who likes this program (or if they do, they haven't been using it long).