Suzumiya Haruhi no Yuuutsu (2006 Ver) only contains 14 episodes that were aired in 2006 and arranged as 2006 TV sequence, it also includes all SPs at that time. This version is ideal for someone who yearns for the 2006 experience.
The 14 episodes of 2006 version in BD source are known to have notoriously poor quality. The BD was upscaled from DVD with strong edge darkening and over-sharpening. These over-filterings resulted in lots of ringing and aliasing. We de-scaled the BD to lower resolutions, fixing the artifacts accordingly, then we upscaled the video using a more "soft" approach. Comparing to the BD source, the pictures look vastly different, with certain parts appearing less sharp than the BD source. These are intended effect from fixing artifacts and unifying visual quality. Please refer to the first five pairs of screenshots below for your judgement.