There is a little bit of getting used to the special language that Kant uses, but it's really not hard to follow if you are familiar with Kant (I am not a philosopher but I want to learn my purpose and how best to be 'good'). He'll use 'synthetic' and 'analytic', the trick I use is since 'synthetic' starts with 's' think 'senses', and analytic is another word for math so think 'math', for 'a posteriori' and 'a priori' (I put them in this order because 'a posteriori' relates to the senses (synthetic) and is after the fact or after experience, 'a priori' relates to 'analytic' before the fact or from first principles or deductively as in a mathematical system. Two other Kantian words are 'subjective' (think 'self' sense it starts with 's' and 'objective' is an 'object' (or thing) outside of yourself.
Kant is really not hard to follow and this work in particular was clearly written such that any one can really follow it because he obviously wants as wide an audience as possible for what he is going to tell the reader. (Now, I will admit that "Critique of Pure Reason' was hard at first but once I looked up those words in the above paragraph I ended up loving what he had to say and how he said it. With Kant you always get a unique way of looking at something and it's not always as important what he concludes as how he gets there. He even says something like that at the end of CPR, but with this book how he gets there and what he says are both well worth the effort).
The reason he wants such a wide audience is because what he's going to tell the reader is an answer to one of the two great universal truths we all seek: 1) knowledge (justified true beliefs) about the world (Aristotle starts his Metaphysics with this fact), and 2) knowledge of the good (or divine) (Plato's formulation). This book is all about the second truth we all want, and to know about the 'good' one must first understand what the good is. This is what he does within this book.
Kant builds a 'ground' based on reason to get at what our unconditional duties are in which we need to grasp the unconditional practical reason (morality) as maxims (universal laws) or as he says 'categorical imperatives'. Or in other words, he uses the infinite to get at our finite understanding of how we should approach life. His methodology is always a pleasure to behold and will teach anyone (including me) how to think better, and his conclusions are one of the best guides on how to live a moral life that I've encountered. I like the Golden Rule (and parts of the Sermon on the Mount), I like J.S. Mill's utilitarian philosophy, and I just love Kant's Categorical Imperatives. A combination of all three is how I choose to live.
In the end, we earthlings, need to understand what it means to be good. All moral philosophy at its root combines empathy with reciprocity of some kind and call for us to be 'good' in some fashion, but 'what is the good (or divine)' is not obvious except usually in some circular fashion, and this book gives an extraordinarily good account for it. Don't worry about the technical language, because overall it is written to be understood, and is an incredibly good self help book that could easily replace almost all the rest of the current best sellers especially the vile self help books which I walk past in the bookstore.