The on-sky separation is easily computed with the separation method, which computes the great-circle distance (not the small-angle approximation):
>>> c1 = ICRSCoordinates('5h23m34.5s -69d45m22s')
>>> c2 = ICRSCoordinates('0h52m44.8s -72d49m43s')
>>> sep = c1.separation(c2)
>>> sep
<AngularSeparation 20.74612 deg>
The AngularSeparation object is a subclass of Angle, so it can be accessed in the same ways, along with a few additions:
>>> sep.radians
0.36208807374669766
>>> sep.hours
1.383074562513832
>>> sep.arcmins
1244.7671062624488
>>> sep.arcsecs
74686.02637574692