I will shortly be signing a contract for this book, and am working almost daily on it. It's a cool idea that was entirely the publisher's (this is the second time in a row; it was also the case with The Catholic Verses), that I have taken to quickly, like the last book.
The idea is to do a vaguely "Summa-esque" (my editor's description) treatment of many apologetic topics. Each one would take up two pages, designed to offer the best answers possible in that space for various objections.
Each section starts with the objection, briefly put (usually Protestant boilerplate contra-Catholic polemics, but also including some theologically-liberal and heretical errors: non-trinitarianism, etc.). I respond summarily (a few initial lines) and at length (3-4 paragraphs). The "objector" replies with further protests, and I counter-reply with another paragraph. Each section concludes with a pithy, relevant quotation.
We want it to be designed to provide quick replies to non-Catholics: a handy source and "witnessing tool" for apologetics. Hopefully, there will be enough depth to satisfy inquirers in each section, while retaining brevity for the purpose of usefulness and practicality. That's the trick. Writing and publishing is all about goals: what one is trying to achieve and provide for the reader.
This is much harder for me to write than any of my books so far, because I have to condense and digest everything and find the "best" material to use. It drives my perfectionism nuts! I always want the best arguments, and many times they are hard to briefly summarize, so it is quite a challenge for me (what Bible passage to actually quote, and which to merely cite, etc.). But little by little, I'll get it done. I've been excited by what I have come up with thus far.
I love the "practical" nature of the work, because my own aim has always been to provide sufficient answers to objections to Catholicism or to Christianity, generally-speaking. The more meaty, in-depth stuff can still be had in other books and on my blog and website. There is a place for both short answers and long answers, and I have done both throughout my apologetics career (despite the stereotype about me that I always write endless treatises - see my own self-parody). I do write some lengthy stuff, for sure (because Catholicism is not a simpleton's religion and has tremendous depth), but I also have a lot of short papers, too, so that is nothing new for me.