I have Drain's book...it is the PACU "Bible". The info in there is priceless. I've found things that anesthesia didn't even know about in it.
But my advice is to wait until your feet are wet to look at ANY book. I've always been the type to buy a book/guide, etc. when starting a new job. I had an excellent preceptor once tell me, "PUT THE BOOKS AWAY and LISTEN, WATCH, TAKE NOTES!" Best advice I ever had.
When I was a PACU nurse I learned all that I could from my coworkers then when I wanted to learn more, I referenced Drain. PACU is so much about instinct and using all of your senses. It's like no other nursing. I :heartbeat PACU and I miss it. In the OR now, but was able to relieve someone for break yesterday in PACU.