there's a whole thread on the anime...but I'll summarize my feelings.
The anime does not reflect the LN well. It might was well be (as @Antipathy put it an 'alternate timeline') or for a different series of books altogether. It's not the worst anime adoption of a JNC novel ever (Ragnarok gets that title, with Smartphone a close 2nd) but it is bad. That being said, as someone who read the LNs first, I enjoyed some of the anime, mostly out of a sense of nostalgia or because a particular episode reminded me of a part of a LN I particularly enjoyed, but I can't imagine that many folks found the anime to be very good without the context of already having read the LNs. My advice: use some premium credits and buy the series of LNs (the premiums get you some quality bonus stories) and only after you get past where the anime covered (Volume 4? I'm not sure) go back and watch. If you can grit your teeth through the CGI sequences, there are a few moments that will make you chuckle, and overall you might enjoy the cour.