I think the model for the New Stadium looks great! The Clear ETFE roof section is an interesting, out of the box thinking way to bring a little bit of the outdoors to an indoors stadium. I remember watching a show a while back that focused on the building of the "Water Cube" in Beijing for the Olympics. It looks like a pretty cool material, and it will give the Vikings and the state a Party Piece Stadium to show off.
However, like others have already brought up, the first thing I thought of was the Snow collapse at the Dome. Out of curiosity I googled it to see if I could find info on the material. I found one thing that is mildly concerning.
The same material was used to build part of the roof at BC Place stadium in Vancouver,
http://en.wikipedia.org/wiki/BC_Place. In 2007 the had a few problems with deflation and had to replaced the ETFE with a retractable roof.
from the link
2007 roof deflation
On January 5, 2007, a tear occurred in the roof's ETFE fabric close to Gate G on the south side where the roof meets the top of the concrete bowl. The tear grew quickly as air escaped through it, whereupon maintenance staff performed an intentional, controlled deflation to protect the integrity of the roof's intact fabric panels. As it was designed to do, the deflated roof rested on its steel support cables 6 metres (20 ft) above the seating and the field. Normally, the roof had a rise of 27 metres (90 ft) above the top of the bowl when inflated. No one was injured during the incident, although rain and melted snow flooded the bowl and subsequently had to be pumped out.
An independent report indicated that an accidental rapid pressurization combined with lightly gusting wind and a location of previously undetected damage caused the tear. The damaged panel was replaced with a temporary one on January 19 and the roof was re-inflated. The BC Contractors Association held an exhibition in the stadium over the week of January 23, during which the roof leaked in several places when it rained. The temporary panel was successfully replaced with a permanent one in June 2007.
later in the article under Renovation.
In May 16, 2008, it was announced that over $150 million in major renovations would be carried out on BC Place Stadium. These included seating replacements, washroom and concessions renovations, and replacement of the ETFE roof with a new retractable roof.
http://en.wikipedia.org/wiki/ETFE