My main issue with the "Head First" format is while the little puzzles (refrigerator magnets, the pool thingy) is doubtless helpful, the books don't come with the actual magnets or a pool. So you're like as not to not do them. Unless you're going to go through the trouble to print them out the pages and cut the pieces out and then do them, you're not getting as much out of the exercise as you might.
That aside, they tend to be well-edited (language and technology) books that leave you with some genuine skills. This is the sort of beginner's book I read even when I've been working with a language for some time because I assume there are holes in my basic knowledge and beginner's books are the fastest way to find those and fill them in.
There's also a certain ego gratification to burning through a book because you had already figured it out, not gonna lie. But in-between patting myself on the back for figuring out how Go's poorly named "slices" work and how it's wonky as far as pointer/dereferences go, I learned things like how Go handles documentation, and its multithreading and testing features, which I hadn't bothered.
I didn't find the Big Picture stuff I was hoping for, which I notice is a very common thing among non-OO languages. Even if it's arbitrary and ill-suited to a particular problem, OO gives you a definite path to organizing and designing very large products. It's not really a knock against what is essentially a beginner's book, but I'm still looking.