Very plug and chug.
Whatever that means in math.
If you're confusing "plug and chug" (I don't remember any calculus problems where I simply put numbers in for variables into an equation to solve) with focusing on technique and clarity over rigorous proofs of every theorem, sure Anton's guilty (he even says so in the preface). Sure, something like say, Apostol (The most rigorous calculus volumes I've personally worked through, and some people would even say that's not very rigorous! Dirty real world applications and all), goes into more depth on topics and justifies the majority of the theorems with proofs, but I got a lot more out of the reading (and working) after understanding the techniques of solving calculus problems.
This is my rub, and it bothers me to my core the older I get, this whole rigor at all cost mentality is silly. It isn't like you can only read
one calculus book and then - that's it! You can't ever expand on what you've learned, ever again! Nevermind that the majority of students learning calculus for the first time are looking to apply it, not study it's underpinning, and you've got one confused dude on the hate Anton gets (Or even Larson, which I personally hate from the narrative style of the text and him completely throwing out the baby with the bathwater.)
To a physics student studying calculus for the first time, which is more immediately apply-able? Technique, or theory?
Have you actually bothered to work through the text before critiquing it?
I stand by my recommendation, it's cheap, so if he doesn't like the narrative style or level of rigor he can toss it in the recycling bin.