Discovery was never bad. It's just different. Some people say it's not what Trek is about.

1. Star Trek has always been about captains exploring. Deep Space Nine challenged that with a commander; Sisko later made captain, but the station itself only moved in the pilot (closer to the wormhole; it's always been in Bajor's orbit) and maybe one other time? But they did plenty of exploring in the Runabouts, and Defiant, the ship they got later. But essentially the action came to them, and that was fine. Discovery is not about a captain. Michael Burnham is a... commander? I forget. On the original ship. Then she's nobody. She gets promoted up but she almost never leads, but the show focuses on her. It's... weird. (And she's a woman... named Michael... pronounced the same as the male name... and this is never explained.)

2. Star Trek has always been about diversity, but Discovery had a gay couple in an openly sexual relationship. It never showed sex between them, but plenty of kissing and intimacy. Discovery also had a non-binary character with they/them pronouns. And as mentioned, a woman named Michael, but she's cisgendered and straight, so that's not why she has a guy's name. Anyway, some people thought it was a few bridges too far.

3. Star Trek has almost always been wholesome. Deep Space Nine pushed the envelope, and while it showed Sisko doing some very bad things, profanity was never part of it, and the violence was mostly PG. Discovery was on streaming, so they had profanity and R-rated violence. There may have even been some mild nudity, I don't recall. This put off a lot of traditional fans.

4. Before Deep Space Nine (i.e. The Original Series and The Next Generation), Star Trek has always been episodic. DS9 introduced arcs, but each episode still had its own identity, and this was true through Enterprise. But each season was its own thing on Discovery, and no one episode really stood alone.

Points 3 and 4, and to some, point 2, put off some older, "traditional" Trekkers who felt that Discovery was made for the younger generation and was not "for" them. And I can dig it. I mean, it does follow the recent-ish films where the ships are flashy, not tacky with their tech. (Keep in mind, the ships were always flashy for their time! It's just, we cling to the old designs and the newer, flashier one just seems excessive, but now, the newer, flashier one is dull in comparison to the ones that have followed it.)

As for Picard, that was purely a sequel to The Next Generation (and to a lesser extent, Voyager, because of Seven of Nine). It was a love letter to the fans of that show, those shows. As purely its own thing, it's a weaker Trek entry, but for those of us who grew up with 80s/90s Trek, it was good closure since the movies were neglecting those characters. Another such show might be Prodigy, which is a more direct continuation of Voyager, but Prodigy stood on its own better with its original cast. Picard's original cast was not very good, but very forgettable.

Back to Discovery, it's very much its own thing, set both before TOS and after anything else (minor spoilers — plot device allows them to swerve around any continuity problems). It did launch Strange New Worlds, which Trekkers seem to like more than Discovery, as that is a straight TOS prequel, showing the (movies/newer) original Enterprise under Captain Pike, who was captain before Kirk. Spock's in it, too. (I have yet to watch SNW, but I plan to. I just finished Prodigy and I like to space them a bit.) Discovery also launched Section 31, the streaming-only movie, which is about as bad as you've heard. The less said about that one, the better — if you want to watch it, you should, and you should do so without worrying what Internet People think about it. It's still Star Trek, albeit some of the weakest Trek out there.

Personally, I rate Discovery above ENT but below Voyager. I have a hard time deciding whether Discovery or Prodigy is better. Prodigy was a computer-generated anime that aired on Nickelodeon and that all sounds bad, but it was actually very good. It might seem at first that Kate Mulgrew (Janeway/Hologram Janeway) is there to prop the cast up, but they all shine so brightly, they don't really need her as much as they think. I liked TNG, DS9, and VOY all better than STD and... whatever we're abbreviating Prodigy to (PRO? STP?). As a child of the 80s, TOS is a bit dated for me, but the stories were so good... that's another one that is hard to place for me.

I recommend you watch it, but if you do, you have to finish the season. You can't drop it mid-season, and if you do, you can't judge it, because the individual episodes aren't meant to be watched on their own. It's meant to be binged. That said, you can safely stop at the end of any season. I won't say it gets worse, but each season made me wonder if it was really necessary, including the first one. Because no, it isn't. Discovery is not necessary for... anything... in the Star Trek universe. It's not really connected. Even Strange New Worlds... they ran into the Enterprise in the beginning of the second season, but then they went away. So yeah, you can safely watch SNW without Discovery and you'd be fine. I do think the first season was good, as far as action Trek goes. And you can stop there, but with the way it ends... you won't. Season 2 was okay, a good mystery, and you can stop there, but you still may want to see what comes next. After that, I think the quality does take a bit of a dive, but then they're in the far future, and you just wanna see more and more of what's left of Starfleet in the future. And it's good enough to stick with. But never necessary. And that's probably the "worst" thing I can say about it.