...I don't recall any in-dialog exposition about why a shuttle couldn't be used...
Someone, either Georgiou or Burnham specifically says they don't have a shuttlecraft maneuverable enough to approach through the accretion disk.
As for my initial take (having viewed the first two episodes):
I liked it. I wasn't blown away, but it was good.
The best part was the characters and their interactions. I was a mite bit worried that, even thought I felt most of the pacing/dialogue issues in the trailers were due to trailer editing, there would be some issues still in the show. I am glad that is not the case. I liked all of the main cast members. Saru and Burnham's sibling rivalry was great. I felt Sarek was good, though not as great as Leonard. I am sad there won't be more Georgiou except maybe as flashbacks. Though I could do without minor bridge character's spouting random technobable in the middle of actual battles or dramatic scenes etc.
Probably the only big thing I didn't like was the dialogue/pacing of the Klingon scenes. While it was nice to not have the Klingons yell about honor every other word (it will still take some time to get used to), the scenes were very slow. It seemed like it was just hard to talk/act through those teeth and armor. The scenes also felt like not a lot happened. Ironically I think some of the problem comes from the holographic display technology. The show producers said they did it so they could have the characters stand in front of each other, instead of being up on the viewscreen. But now, instead of scenes that normally would have taken place with all the characters physically in the room (the meeting on the Klingon ship) with all the energy that creates, they can be "in the room" via hologram. But there is no physical presence, no sense of immediate confrontation (between, for example, Kol and the albino guy), and instead we get the other klingons projected as floating entities on a different level, different size, and all fuzzy. Put the actors in the same room and reduce the size of the teeth prosthetics and you would fix 75% of the problem.
The graphics were amazing. The ships looked cool. The rooms, displays, etc. were all very good. The opening credits were very nice.
I am looking forward to seeing the rest of the main cast and the Discovery and their whole plot. But man that sentencing? (In 100 years, you get a slap on the wrist and get to walk around New Zealand for a while (see Ro, Paris).) I think an unanticipated upside to this whole "second pilot" structure, is there is so much more to discover yet about the show.
One minor thing I didn't like was that when an episode ended, there was nothing telling you that it did (no climactic music, no producers credits), so I sat around waiting for more and there wasn't any until the next episode trailer. I don't like that at all; but I guess that is modern TV/streaming - trying to keep the viewer watching the channel/episode through another commercial break. Ugh.
So, just first thoughts. I will have to watch again to really get my head around it.