I checked into Extreme Hotel last year for a two week stay. It was a bit of a disorganized shit show and the hotel was overall not very well maintained. My bed sucked too.
By the second day I moved to the Hotel Aqualina http://www.agualina.com
a few hundred feet down the road and it was 100 times nicer. Well maintained, CLEAN, and really nice helpful staff. And far better feeling of security. It is right on Kite Beach too and has a nice pool and area to clean and organize your kites etc.
I made a deal with the front desk for two weeks that was only a bit more than Extreme would have cost. REALLY well worth it.
I still went to Extreme's bar/restaurant for breakfast which was good.
A lot of cool, interesting people go to "Ali's Surf Camp"http://www.alissurfcamp.com
It is not on the beach but the vibe is worth it to some and it is one of the least expensive places to stay in Cabarete. I went there for dinner many times and the dinner is AWESOME!