It should have been good, and I wanted to like it, but in the end I found REC to be extremely annoying. For me it was neither scary nor particularly interesting as the story was far from unique. I understand the whole horror movie style of stupid people doing stupid things, but the reporter (either on her own or under guidance of the director) went beyond stupid and hit annoying pretty fast. Her constant screaming when there was no need, heavy breathing when she hadn't moved in ages, and overall panic level that she could turn on and off at the flick of a switch was so unbelievable it prevented me from being immersed in the movie and had me wanting to strangle her. I was praying to God (and I'm an atheist) that she would die a horrible and painful death as she ruined the entire film for me with her shrill voice shouting over every scene from on and off camera.
If I could somehow manage to block out every annoying sound that came out of her mouth, I'd probably say the the movie managed to be entertaining and well made for being such low budget flick, and would have certainly recommended it.