What are the differences (pros/cons) of solution and solid state NMR for structural biology?

A particular advantage of solid-state NMR and NMR spectroscopy, in general, is its ability to provide information on the dynamics of biomolecules.

Pros:

In solid-state NMR spectroscopy, motions on a broader timescale (from the nano- to the millisecond timescale and beyond) can be detected. For example, the nano- to millisecond timescale can readily be explored by measuring the spin–lattice relaxation in the laboratory (R1) or the rotating frame (R1r), while real-time solid-state NMR allows the course of protein refolding or of enzymatic reactions to be followed.

There is no protein size limit in solid-state NMR spectroscopy.

In liquid state, the anisotropic interactions give rise to fluctuating local fields which themselves manifest as relaxation effect in the spectra. In contrast, the rapid tumbling of molecules is absent and the anisotropic interactions give rise to a distribution of resonances reflecting the distribution of molecular orientations within the sample. These distributions, on analysis, can provide wealth of information: the anisotropic interactions experienced by the nuclear spin, the local electron distribution around a nucleus, and relative proximity between individual spins.
Using the structural and dynamic information encoded in the interactions experienced by the nuclear spin, it is possible to determine how the structure and dynamics present within membrane proteins relates to their function, and how these molecular species interact within the membrane.

Cons:

In solution state, resolution is provided mostly by nature because the anisotropic spin interactions that can broaden NMR lines are motionally averaged. In the solid state, motional averaging is less efficient because of reduced mobility, and considerably broadened spectra are acquired in this case. Line narrowing, therefore, must be performed artificially: manipulation of the Hamiltonian to dissect the anisotropic interactions or to suppress their influence on NMR spectra in a controlled manner.

With regards to the protein size, technical challenges remain to be solved before dynamics can be routinely measured at atomic resolution in large proteins.

Additionally, with respect to solution state NMR  integral membrane proteins embedded in detergent micelles are still challenging.