[TLDR further down]
I woke up at 1am to catch both digital stars and the concert and I sadly have to say I could have just slept. Digital stars was fine, I didn't come for that but still, good artists so I had a good time but the concert itself... Luckily I've read in other posts that I wasn't the only one who thought this: it was fine. Out of the songs played only one was actually popular (excluding toy box and plaything which were made for this event) and I fully enjoyed, the other ones were by artists I've never heard of and didn't really quite catch my interest (I'm not saying lesser known songs are bad, not at all, but there is a reason why popular ones are popular). When I watched this year's magical Mirai stream there were also songs like that but I've actually found a couple I've liked and added to my Spotify together with many others I already knew and was excited about.
As for the quality, I liked the stage but when the camera zoomed into the live band, the members had a pretty choppy frame rate.
On YouTube it was streamed only up to 720p, on Twitch it was 1080p but (not sure if it was my connection but at 3am who is using the internet, plus never had this issue) the bitrate must have been kinda low. Dark scenes, fireworks and confetti made it possible to pretty much count the pixels.
And to top it off, it felt more like a compilation of songs than a concert. It was like song-black screen-song with Miku talking once in a while with very long pauses of silence (totally understandable, there is no crowd to cheer and make some background noise but at least putting some background music could have helped)
So in a nutshell, it's Miku so I can't be really disappointed but I didn't really feel the need to save the footage like I did for Magical Mirai even though I've appeared in the end credits which was cool.
I'd say, if you want a concert go for a live one even if it's streamed online. If you want to see animations than just go for YouTube. It was a cool idea during the pandemic (not that I've seen it but it was a thoughtful choice) but this year it felt kinda wasted in my opinion.
Glad to see that many enjoyed it really much though. Maybe I just had too high expectations
I think it just boils down to personal preference. You might make a song using the japanese vbank and some people will like it while making it with the japanese one will appeal more to someone else. IMO it's a gamble really. You should check both. Maybe you're able to get a better result out of one compared to the other.