First, I've been a diehard Mobapad fan since the release of the M6 HD, which I think are absolutely perfect. I saw the video from Rerez on YouTube and the second I realized all the buttons, and especially the Dpad, use microswitches, I instantly ordered and never used another pair of joycon since.
On to the M12 HD. They are pretty great, but I really think it was a mistake to not make a model that has the best from the M12 HD and the M12 S model.
The HD do not charge in sleep mode, and though there is a work around, and they're adding the charging grip, it is still disappointing.
They also only have 6 axis gyro, instead of 9 axis like first party joycon or even the M12 S model. It's still pretty good, but obviously not as accurate as 9 axis gyro.
These are my only major gripes.
Having said that, I still really like what they got right. The excellent microswitches are back (seriously, I play a lot of shmups and a ton of Virtua Figther--the Dpad is fantastic) and feel great.
The new TMR glide sticks are a great new edition, and feel great.
I don't usually care about rumble when playing in portable mode, but the HD rumble is so much better than standard rumble that the S model and their major competitor uses in their joycons.
Overall i'm very happy with whats great, but disappointed with the couple of negatives. I hope Mobapad releases a newer, more complete model that addresses the issues in the future. Until then i will happily use the M12 HD for 99% of my Switch2 portable playtime (they obviously don't have mouse function, so I'll have to use the first party joycons for those few games)..
They're not perfect like the M6 HD, but still great. I'm happy with my purchase.