I got my nance a little less than a week ago.
I definitely felt like I sounded funny the first few days. People that knew me admitted that I did sound a little different, but only after I asked them. One friend said that I just sounded more deliberate in my speech. My mom said that mostly it sounded like the sounds that are made in the back of the mouth were a little muffled.
The button up front doesn't really seem to be affecting my speech that much. It's really smooth and tapers down very nicely to the surrounding palate. Also, I've got a small area between the button and the back of my front teeth where my palate is. I think for the first day or so I had a little trouble with T and D sounds because I had to get the tip of my tongue to hit the right spot just in between there. But now it seems to hit right on most of the time without any effort.
The part that messes with my speech more is the wires going back to the molar bands, because they interrupt the way my tongue hits the roof of my mouth more. So sounds like CH, J, SH, R, and other stuff that gets made in the back of the mouth were a little difficult. But I've worked around that some.
But I am speaking better now. Sometimes I don't sound odd at all. If I'm tired or being lazy about speaking, it sounds a little garbled or sloppy. But if I'm careful when I talk, things are mostly okay. And this is less than a week in. After 4 days, my mom said that I was sounding a lot more clear and like myself. I think a lot of the changes are things that I notice, but other people don't really hear. People who know me and are used to hearing me talk can pick out the differences, but I bet most strangers wouldn't think anything of my speech at this point, for the most part.
Other than getting used to speaking with it, it hasn't bothered me at all. The wires going back to the molar bands made my tongue sore for the first day or two, but that was it. And not horribly sore, just enough to notice.
Pretty much with the speech, as long as I slow down and enunciate properly, I sound completely normal. If I try to speak too fast or if I'm lazy and sort of slur my words a little, things get a little sloppy sounding. But I've been able to have conversations with lots of people and nobody just sits there staring at me like I'm speaking a foreign language.
Here is the farther back view of the nance. You can see the wires going back from the button to the molar bands. I don't know why they have the little squiggles in them, but they all seem to. Must serve some purpose. Anyway, those are the things that get in the way the most. They are also the most fun to play with, too. You can see that they lie very flat against the sides of the palate, though. Nothing sticks out at all. I can just barely pretend like I can get the tip of my tongue under the straight part of one side where it goes by an extraction site. But really, it's right flat against the palate and doesn't get in the way of eating or brushing, and after some practice it doesn't get it the way of speaking much either.
Here is the front picture of the nance, where the button is. Again, it's very close up to the palate, and shaped very nicely so that it is smooth and transitions nicely from the appliance to the palate.
So I guess in summary, it's definitely not uncomfortable after the first day or two. I found the adjustment period with the nance to be much more comfortable than the braces themselves. And the speech is more of a personal thing. It's definitely going to be impacted for a few days or a week or so. After that, you should be sounding fairly normal as long as you speak carefully. You may not sound exactly like yourself when you listen to yourself, but you probably won't sound weird to other people.