Two new native QGIS raster reclassification algorithms have been added to Processing. These are simple to use, yet fast and stable, and work for ANY raster layer type supported by QGIS!
Reclassify by layer: reclassifies a raster using the ranges specified via min/max/value fields from a vector table
Reclassify by table: reclassifies a raster using a fixed table entered by users in the algorithm dialog