I loved 'REC', but my experience was different - I do not speak Spanish and my copy had no subtitles. It was still fun, scary, entertaining. So my take on 'Quarantine' was 1) I was glad it was shot identically to 'REC'; 2) It was fun to find out what the plague was :^); 3)Still very scary; 4) Open to sequel.
No slight to Jennifer Carpenter, who does a great job, but one must see 'REC', however, to enjoy Manuela Velasco...