Yeah, I might have overstated it a bit, but it's just not clear what pushing a button marked "message" will do when my phone is ringing. The same with "Remind me" actually.
Is the message button going to take me to the messages app? Is it going to take me to the voicemail part of the phone app? Will "remind me" take me to a calendar and make a reminder for ...?
I like the idea someone else had on this thread where it's just Accept or Decline, and then Decline takes you to some other options.
Maybe this is one of those things we will just learn, it will become the new standard, and we will wonder how it was ever confusing previously, but for right now I think folks will be confused.
I do like the new Phone app overall though. The current one has even more egregiously bad UI problems. After five years of using iPhones I still have problems using the voicemail, and trying to look at calls and contacts without inadvertently calling someone. It's really poorly designed at the moment so anything new is probably a good thing.