What I'll miss about DSC:
1. Saru, Culber, Stamets, Vance...all really good characters who made their mark on the franchise in my opinion. I would include Tilly here, but she's already off the show.
2. The weekly excitement. DSC is really (still) the only show in the franchise where it still feels like literally anything can happen week-to-week. It's a very interesting show in that way, and it's part of what made it so engaging and exciting.
3. Some of the character dynamics. Saru/Burnham was a really interesting dynamic, for example...I'm not sure it was ever fully explored, but I always like the two of them.
4. The sets and production design for the most part were great, although I have absolutely no care at all for the S3/4 props and designs. They all seem so forgettable and generic.
5. The high-paced, heavy action orientation that reminds me of the most electric parts of the Kelvinverse movies. That's DSC's niche...
6. Secondary characters like Owo and Detmer.
What I won't miss about DSC:
1. Throw-away characters who had early potential but never developed properly. Adira, Book, Gray, Reno...I'm looking at you.
2. A lack of internal world building and consistency. It is very frustrating to me that the simplest things, like the visual fx consistency for phasers and torpedoes or, as others have mentioned, constantly changing uniforms, have made this series feel very disjointed and unconnected to itself. Lots of people complain about inconsistency with past continuity and canon. I don't care so much about that, but the lack of internal detail and consistency WAS admittedly frustrating to me, even with the timeframe shift.
3. The theme music. Compared to the other modern shows, the main titles theme really kind of sucks...as does the montage they play over.
4. As alluded to earlier, the S3/4 prop design and "updated technology" (super comm badges, detatched nacalles, programmable matter, etc) is......I don't know.....really not very good. I couldn't even tell you what a DSC 31st Century phaser looks like. Most of the new designs are painfully forgettable, as is the entire future setting. I'm hoping S5 adds something interesting to the mix.