I have been playing with the new manual input, number and symbol entry, and with a few differences? I don't see much advantage with this system over just switching to the iOS keyboard.
The magic tap works very well, and the ability to flick right and left if I accidentally enter a wrong letter is nice, but I still need to go to the iOS keyboard to switch text fields and to send this email.
I understand this is the first incarnation of this feature, and I'm sure it will be improved in future builds, but at this thyme, at least for emails, I still prefer to use the app.
I typed this email with both the custom keyboard and the app, I was much faster with the app, and I could review what I had written with the raise to speak feature.
I also realize I am in the minority with my opinion but dealing with only the app seems more stream line than using three keyboards.