It's not completely fair to judge the quality of this paper by the first few references (8 and 25, in particular), but it does make me extremely dubious. It's not really appropriate to cite Ed Glaeser in an urban modelling paper (or anywhere, really, other than as a cautionary example), and that interpretation of Bettencourt and West won't bear much scrutiny either. I won't address the…contributions (I work in a department that does a lot of urban modelling and ABM – it's cited in the paper – but I'm not a modelling / ABM person myself)