I think the season still holds up. I also am of the opinion that the fourth season is the best season of the series. I like it better than the first season, which had been my favorite before. Some people think they dragged out contact with Species 10-C, but I disagree. I think it couldn't be as easy as 1-2-3 and happen as fast as "wham, bam, thank you ma'am." Communicating with a species with whom the Universal Translator won't work, it will take time, and we got to see that here.
When the Discovery crew finally began to truly communicate with Species 10-C, it reminded me of when Kirk was able to communicate with The Companion in "Metamorphosis" (TOS). For you non-TOS Fans who don't know what I'm talking about, look it up. It was also the opposite of "The Changeling" and Star Trek: The Motion Picture where Nomad and V'Ger wanted to exterminate "imperfect" or "not true" life forms. Species 10-C didn't realize the inhabitants of the Milky Way were sentient and stopped using the DMA once that was communicated to it. This is pure Star Trek. It doesn't get any more Star Trek than that.