My experience with Nicholas Humphreys Northampton branch was good and hassle-free. In short, you keep your side of the bargain and they keep theirs. I rented via them and had no problems at all. Any minor issues were dealt with pragmatically and fairly. They were efficient in setting the tenancy up and similarly so in closing it down cleanly. In between times there were relatively few interactions. They have good friendly staff which is another plus.