As with many other posters here, I was not a fan of the "get juiced up and fight Klingons" scenes, from basically any angle. I didn't really care for the fight scene in general, and the stimulant stuff just seems whacky.
However, I'm inclined to give them the benefit of the doubt here, because this sort of thing is not totally foreign to Star Trek: in Amok Time, McCoy gives Kirk an injection of something which allows him to temporarily match Spock's strength and fighting ability. It's one of the many, many "well why don't they always do that?" Things that pops up in Trek and in TOS especially, and my hope is that the long term plan here is to settle that question. Perhaps this thing has some truly nasty side effects, or it's extremely addictive; in any case there's plenty of reason not to make it standard or even permissible gear.
Branching slightly from there, it's remarkable how much sketchy stuff doctor M'benga has already been involved in. First keeping his child in the transporter buffer and then releasing her to live in a cloud, now revealing that he keeps vials of hulk drugs about his person at all times. There's plenty of grounds here for us to surmise why he is no longer a CMO when he shows up in TOS.
Which leads to the third point that's beginning to worry me about this show: we're seeing a number of character arcs which we already know the ultimate resolution to, and it's not the resolution that I find myself rooting for as I watch these characters. Spock and Chapel definitely don't wind up together; Spock and Chapel both become much more emotionally withdrawn; M'benga gets himself demoted; T'Pring finds a flagrantly sociopathic way out of her relationship with Spock. And,obviously, Pike suffers his horrific accident. It's a pretty depressing slate of events inevitable occurring to a number of characters who I didn't care about all that much before this show (excepting Spock, obviously) and have come to really enjoy watching here.
The "well we know they won't die" is an often cited rebuke for why prequels with classic characters aren't always a great idea, but "we know the general arc of their lives" is arguably more impactful. Most characters don't die during their shows, and if the writing and acting is good enough I won't care that an outcome is preordained while I'm watching. But knowing that storylines I am emotionally invested in are doomed to end badly hits me at times when I can and will actually think about it, and It's really not a good mix with what should fundamentally be an optimistic show.
I'm personally okay with knowing the destination, as long as the journey is worthwhile.
M'Benga was a blank slate on TOS, so I'm enjoying the character that they've pretty much invented wholecloth for this series (I certainly find this current direction more interesting than the story with his daughter in season one).
Chapel is another big departure from the TOS portrayal, but I'm enjoying the trajectory as she, I don't know, "flirts with destiny".
Spock is full of surprises as they connect the dots between the smiling Spock of "The Cage" with the version seen on TOS proper.
Pike...well, Pike is probably the one I'm least happy about, because I thought they way they had him confront his fate on "Discovery" was perfect, and everything they've done since then has diluted it somewhat for me.
But for the most part, I'm enjoying the journey, even if I know where they're going.
Yeah, I guess my problem isn't knowing the destination, it's knowing that the destination is going to be pretty rough in ways that run counter to this show's general vibe. Which really is pretty similar to my broader frustrations with Discovery's "the distant future includes 120 years of horrific geopolitical strife where basically everything your heroes fought for falls apart". I really want to believe in the happy ending, you know? Even when the concept of an ending doesn't actually make real-world sense.
A lot of it does have happy endings, or at least not overtly tragic ones. Spock do goes thru it, but ends up in a very good and important place, and is deeply at peace with himself for decades after all this stuff wraps. We don't really see how Chapel wraps up, but she gets her MD and clearly stays in Starfleet, and so far as we can tell gets over Spock. And Pike gets "the illusion," of course, which is about as happy as any person could be, given his circumstances.
Trek isn't all happy events with clear closings; there were a lot of tragic endings in TOS, for example. Even TWOK is pretty much a tragedy, taken in isolation -- Kirk's hubris in deciding to exile Khan causes a lot of death and pain. Hell, even the resurrection of Spock comes at the loss of both the Enterprise and Kirk's only son.
As long as the pain and tough times have narrative and character meaning, I'm more than OK with them happening because we know so much about how things do work out. Trek reminds, on the whole, a positive and uplifting look at how we can live.