IFSTA is now at the 5th edition (2017), while this prep is 4th edition.
I just took my hazmat exam for FF1 and this app helps but, to an extremely limited amount. Most questions on the exam involved military placards, highway transports and other main objective learning materials which this did not cover. This is useful but, I would definitely not recommend it. Know the limitations or you ERG and many of the terms/definitions of tankars and where valves are located and you'll be solid, good luck!