We spent two nights at the Merton. I will start by listing the positives: the beds were comfy, very good mattresses and the staff was friendly, helpful and considerate.
However, the hotel is in dire need of a refurbishment. It looks very dated inside, whether we're speaking of the common areas or of our room and especially our bathroom. The toilet flush required a lot of pumping before achieving adequate results. The shower was in a bath tub. There was hardly any water pressure.
Breakfast was not very good either, I'm afraid. Some of the pastries were dry (left-overs from the previous day?), the sausages were clearly of the cheap variety and the scrambled eggs had no taste whatsoever. Thankfully,the orange juice and the coffee were nice and there was a large amount of seasonal tasty fruit.
We didn't try any of the restaurants on site in the evening as the breakfast really put us off.
All in all, I don't think we'll be going back to the Merton. It's probably a good place for families with young kids to stay in, as there's a large indoor pool with slides and flumes.