Went back and rewatched episode 8, and I'm still convinced River Song's wording could go either way. She makes two comments that directly or indirectly reference his appearance, so far as I could tell.
At first she says, "Going by your face, I'd say it's early days for you, yes?" which is the closest she comes to saying that this is the same Doctor she knows (physically). I still say it could be interpreted differently, though- "going by your face" could easily refer to his expression, which is one of puzzlement. She seems (to me) to mostly be looking at his eyes.
Then, just a bit later, she makes the comment about "Look at you. You're young." So, obviously she knows him as an older man- either older in this form, or else just an older body in general. But she doesn't stop there, "Your eyes. You're younger than I've ever seen you."
That last bit, to me, is what really makes it sound like Ten is a different Doctor than any/all of the others she's known before.
In any case, who knows. I imagine at some point we'll get some kind of continuation of the River Song/Doctor story.