Things I can think of:
- able to do full S parameter measurement (S11, S21, S22, S12) without changing connections.
- flexible as has 2 outputs and 4 inputs, no hardwired directional coupler/splitter
- can display up to 4 traces from 4 separate inputs
- separate impedance measurement as well as vna/spectrum modes
- Able to sweep not just frequency but also power, DC bias can be swept.
- built in BASIC programming
Disadvantages:
- a big heavy beast
- on some settings (narrow RBW) can be very slow.
- needs e.g. 41952 test fixture to provide splitter/directional coupler
THe attached user guide might give some idea on what you can do with it. I find it very useful