R1 appears to be well served with various DVD versions of The Descent. There appear to be separate releases to cater for those who prefer to see the film in its original theatrical ratio of 2.35:1, as well as a 'full screen' version for those who prefer the butchered appearance.
The R1 'Unrated Widescreen Edition' would be my pick as it includes the correct aspect ratio for the video transfer, as well as these extras in addition to those on the R4 version:
- audio commentary with director and crew
- English subtitles
- interview with the Director
- stills gallery
- cast and crew biographies
Although keep in mind that the R1 version has the slightly shortened ending
There is also the R2 version which has been out for some time. This includes a DTS soundtrack in addition to the R1 extras listed above.