Depends on how critical you are over picture quality. In this day and age a recent I-phone or the equivalent is perfectly adequate for most purposes, but they lack the flexibility of a decent SLR with wide angle and telephoto lenses - but do you need that much flexibility? A phone weighs practically nothing and takes up very little space. The SLR and its accessories is quite the opposite.
Also - worked properly photos on a phone can be instantly saved to the cloud or e-mailed to your home - so even if the phone is lost, stolen or strayed you haven't lost what you have already acquired. You CAN achieve this with a discrete camera, of course, but it is another process to go through.
One thing to bear in mind - it is much more difficult to hol a phone steady than it is a 'proper' camera shaped device - and it is more difficult to use in bright sunlight - difficult to see what you have on the screen.
Frankly, if it were me, and it was a once in a life time opportunity, I would take TWO decent cameras - but I don't know your situation regarding luggage etc.. On the other hand, if it is a run of the mill holiday I would probably be happy with a decent camera phone unless I was expecting photo opportunities that needed the flexibility of a 'proper' camera with accessories.
Hope that helps
Mike