I assume that you are reading these reviews before entrusting Crestons with your deposit or that you are experiencing difficulties during your tenancy. I did the same seven months ago, I would strongly suggest using another company. Crestons are not the worst lettings agent in London however they are disorganised and very poor at client service. Issues with my tenancy included various technical faults that never have been fixed, no rules for a building of multiple occupation (which is requred when you have young tenants), no inventory, no mention of the free internet, free cleaning service and I now understand after my own investigation that my council tax was never paid though I paid this as a part of my rent; this has resulted in a court hearing. Deposit was held with a tenancy deposit scheme however Crestons never issued instructions on the return of the funds and went over the period for informing me of deductions. Their lack of communication, failing to respond to emails and calls was incredibly frustrating. A real indication of the standard of this organization was their lack of interest in trying to lease me another property despite being a good tenant. A sales agency with little to no interest in its tenants.
What agent could do to change your mind?
If this company communicated with its customers and had a simple written procedures for inventory / faults reporting. / items included in rent / tenants regulstions / feedback on council tax payments they would be 100 % improved... but they do not.