I think it depends on your needs.
I'm currently integrating a fully Physicsystem to miniB3D with Newton as the working engine in the background and it works very well.
I don't know much about ODE so I list here some advantages of Newton only(so no guarentee that this is right):
Newton:
very accurate, a bit slow compared to other physic system due to this
highly complex systems are possible
HW support in the next versions
best complex mesh collisions system I've seen
Easy Character Controlling, but as everything you have to play around with it to understand whats going on under the hood.
Hope this helps you a bit.
I'm currently integrating a fully Physicsystem to miniB3D with Newton as the working engine in the background and it works very well.
I don't know much about ODE so I list here some advantages of Newton only(so no guarentee that this is right):
Newton:
very accurate, a bit slow compared to other physic system due to this
highly complex systems are possible
HW support in the next versions
best complex mesh collisions system I've seen
Easy Character Controlling, but as everything you have to play around with it to understand whats going on under the hood.
Hope this helps you a bit.