http://forum.doom9.org/showthread.php?p=1398676#post1398676
-Allows any size and PAR input and output ('outwidth', 'outheight', and 'PARout' are used to define custom target sizes)
-Allows any deinterlacer
-Supports progressive clips by 'prog' boolean, which will bypass deinterlacing and go straight to cropping, scaling and/or boxing
-Has a revised box function that does pillar or letterboxes depending on input and output shape
-Contains ep0 and ep1 parameters, to allow extra parameters for resizer (taps for Blackman and Lanczos, b and c for Bicubic, p for Gauss)
-Contains PARin and PARout parameters, to specify custom pixel aspect ratios (assuming presets don't properly handle your footage)
-Has lost the 'croptop' parameter, its functionality replaced with 'vshift' ('hshift' also available)
-Features 'boxcolor' to set color of pillar/letterbox (integer, either an RGB value or one of the global variables defined in AviSynth 2.5\plugins\colors_rgb.avsi)
-Also features 'boxbgblur' to change amount of blur for "boxbg" size modes
-No longer has YV12 conversion built in; this must be handled before SimpleSlug is called. If you're using RGB footage and an RGB deinterlacer, you won't need any conversion. Same for YUY2 with a YUY2 deinterlacer. By default I'm using TempGaussMC, as always, so you'll need to produce YV12 input with either the 'pixel_type' parameter of your source filter or a ConvertToYV12(interlaced=true) filter before you run SSU.
-Defaults output sizes to mod 8, but this behavior can be changed with 'modw' and 'modh' (will always Floor to the nearest multiple that's below the target output size for a given axis)
-Uses a greater number of TGMC defaults for the "balance" 'qual' setting; with the perspective of some time, I see now my changes had a tendency to make video look too artificial. Bringing back TempGauss' defaults makes for a better result, to my eye. You can certainly adjust things to suit your own taste, if you feel so inclined.