The user representation learned from the reviews is the summation of the contextual representations of reviews weighted by their attention weights: Although the user representation u r learned from reviews contain rich information of users, there are some latent characteristics of users which are not described in their reviews but can be inferred from the rating patterns.
we also represent users using the embedding of their IDs to capture the latent factors of users, which are motivated by traditional recommendation methods (Koren et al., 2009).