Old Ideas are New Again...
I like this minimalist shelter. I also own the older brothers to the current Twin Sisters, the 2003 and 2007 models of the Twin Peaks, also manufactured by MSR. Years ago, while camping in hot weather along the Appalachian Trail, I thought to myself (while sitting in my Chinchilla-colored 2003 MSR Twin Peaks), this is a great shelter -- if only there were a back door and another vent in it.
Wouldn't you know it? Great minds came to the same conclusion, and they also added a snow/wind skirt on it as well (also found on the blaze orange original Twin Sisters). I must admit that although I'm impressed with this current Twin Sisters (now produced in a mustard yellow color), I really wish that MSR would go back to the Chinchilla (Tan) color, which would help me to "stealth camp" more easily.
I also love the two poles they now add to this shelter. This allows the user to carry them or to leave them at home and to use trekking poles (as was common practice until this year's model). The poles weigh about a pound, so decide whether you need your trekking poles to go for water or to do blue-blazing into town, or whether you'd rather save the additional weight.
This shelter is not for the novice, however, since your lifestyle must help to prevent condensation (venting, bagging of wet clothing, etc.) and placement of this floorless shelter requires well-drained ground. I have never personally set this up in deep snow as a ski shelter, but that requires another set of skills as well.
I personally produce and carry my own TYVEK floor, sewn into a two-inch high bathtub. This system is superior to the optional MSR footprint and costs less as well. The ultimate modification would be a skirt of no-see-um netting for hot summer/buggy use, but perhaps this will be found on next year's model.