Myself and my partner stayed at the Benimar begining of May 2013.
It had everything you could ask for really. It was fairly quiet away from the bars and clubs, ideally located in between Old Town and the Square. I noticed that they do not accept hen/stag dos which we appreciated. There is a great supermarket just behind the building almost which is cheap for both food and alcohol. It's also just a 10-15 minute walk to the train station. I suggest you visit Denia, it's about 50-60 minutes on the train but worth it.
The apartment was big, with a separate bedroom with 2 twin beds. There was a safe and internet both at an extra cost (don't remember how much but both reasonable) and aircon and heating was free which was a great bonus as it could get cold at night in May. Many apartments in Benidorm do not have A/C or heating at all. I looked like all the apartments had big open balconies great for sitting outside.
One drawback was that the apartment did not have an oven so cooking was a bit limited unless you fried or microwaved everything. Apart from this, the kitchen was great, there was even a washing machine.
There was a smal pool outside and plenty of sun loungers and chairs for those days when you didn't feel like going to the beach.
Towels/bedlinen only changed once per week, but this is just how it is in these rental apartments in Benidorm. Personally I quite like being left alone without cleaners knocking on all the time.
We hardly saw any staff around during out visit but pleasant every time we did meet them.
I think it was €150 deposit which was returned fully at departure and €30 for late check-out which seemed fair. No problem getting the key at check in either.
All in all a comfortable stay. Would recommend to all.