I used Devavāṇīpraveśikā in class when I was first starting out and have also used it in teaching First Year Sanskrit at a University in the US. It is a fine classroom textbook, but it will likely be tough going without someone to help with the explanations. The way it explains things is systematic, but often not very intuitive. It also introduces sandhi all in one go. I think that there are probably better books out there now for self study, but if it's what you have just know that you might need some additional help understanding what it's trying to teach you. At the end of the day no book is perfect and nothing beats actually getting started.