I sent out a blanket email to a few agents asking for properties in the Reading area, and Parkers were very quick to get back to me, and gave me a lot of detailed information quickly. After one phone call I had five viewings booked all on one day, some of which I hadn't thought of looking at and were suggested by the agent herself. Once we'd found a potential house we made a couple of requests regarding what furniture was provided and the monthly rental price, all of which were met.
My only criticism would be that during the viewings we were told that in some cases we would be meeting other people there who also wanted to see the property. I wasn't terribly keen on this, as it can be quite awkward, especially if both groups want to make an offer! I would urge Parkers to ask prospective tenants in advance if they're OK with this, but it is a minor quibble.
Overall I'd definitely recommend using Parkers in the future.