  The aim of this paper is to summarise the basic arguments and the intuition
bolstering the RFOT picture for glasses, based on a finite dimensional
extension of mean-field models with an exponentially large number of metastable
states. We review the pros and cons that support or undermine the theory, and
the directions, both theoretical and experimental, where progress is needed to
ascertain the status of RFOT. We elaborate in particular on the notions of
mosaic state and point-to-set correlations, and insist on the importance of
fluctuations in finite dimensions, that significantly blur the expected
cross-over between a Mode-Coupling like regime and the mosaic, activated
regime. We discuss in detail the fundamental predictions of RFOT, in particular
the possibility to force a small enough system into an ideal glass state, and
present several new ones, concerning aging properties or non-linear rheology.
Finally, we compare RFOT to other recent theories, including elastic models,
Frustration Limited Domains or Kinetically Constrained models.
