I tried to find the closest pieces of clothing from the H&M collection that resembled the Matthew Williamson Spring or Summer 2009 collection. Here are the closest items:

The blue is much more florescent in the H&M version. The volume is there but not much else.

The peasant shirt is much closer in comparison. The “mosaic sequin peasant blouse cream” is much more off white than the H&M version. At $99.90 you can get something close.

The dress, however, is miles away from being close. At $99.90, you’re better off getting the peasant shirt.
Overall, the Matthew Williamson for H&M collection is not that close to the Matthew Williamson collection. The color pallet is reminiscent of Matthew Williamson, however, the silhouettes and fabric prints definitely do not resemble anything Matthew Williamson-esque. It’s like they took basic H&M dresses, tops, bottoms, and painted H&M clothing with colors and vague shapes that somewhat resemble Matthew Williamson from afar. Besides the peasant shirt, the collection as a whole is not worth the extra dollars you would spend per item at H&M.