The behaviour of exciton-polaritons. L.V. Butov and A.V. Kavokin in Nature Photon. 6:2 (2012).  What the paper says!?

On what they agree (and definition of "coherent state" as "condensate in momentum space"):

Several experimental groups have demonstrated that exciton– polaritons — quasiparticles made from a mix of light and matter — can form a coherent state (that is, a condensate in momentum space) in a semiconductor microcavity 1–4.

However:

However, there is little agreement in the community regarding the nature and associated terminology of this condensate: is it a Bose–Einstein condensate (BEC), a laser, or something else?

The authors (Butov in particular, probably) do not wish to call this BEC (or superfluid)

Here we wish to point out that describing polaritons and their condensate in terms of a BEC and superfluidity may be misleading.

Arguments include:

• coherence brought by the photon component
• no equilibrium

There is also, and in fact a more serious, attacks on superfluidity, with main complaint being the regime of resonant pumping, which leads to a series of alternative explanations («screening a disorder potential by repulsively interacting excitons and parametric instabilities in a polariton system»); Also the scattering time is challenged, e.g., «In analogy, although the electron scattering time in a metal can be larger than the experiment time, this does not make the metal a superconductor.»

Conclusions:

The polariton condensate is a new type of condensate that is different from a conventional BEC.

and

The term ‘polariton laser’ does seem to be appropriate for a polariton condensate. The physics of a polariton condensate, although different from that of a BEC and superfluidity, is nevertheless rich and interesting.