I haven't weighed in on the new uniforms yet, been waiting to really think my opinions through. This is basically the first time in my lifetime that any of my favorite teams have made a significant change to their branding.
My opinions on the previous uniforms: They'll always be associated with arguable the strongest 20-year run in NFL history, and as a fan, that obviously clouds my judgement. However, I'm generally a pretty big fan of the previous set. The home uniform was a classic. With the exception of the side piping, there really wasn't a flaw in my opinion. The colors were balanced very well throughout, and I loved the combination of navy and silver with red as an accent. It also combined white and silver in the same palette in a way that looks good, which is something that can be difficult to do when balancing them with two other strong colors. The number font was traditional but distinctive. The road uniform is a little worse. I love white striped socks, but the ones found on this uniform made little sense and were a holdover from when Adidas was the manufacturer. The side panels don't look good, but they look better here than on many other uniforms of the same vintage. The stripes on the pants are boring, and silver is only found on the helmet. The color balance is not optimal, but the overall look is still a good one.
The new uniforms:
Helmet: The helmet is unchanged, and I'm very happy about this. The silver shell used by the team is fantastic, and the red facemask is distinctive. While a polarizing feature, it's always been one of my favorite parts of the uniform.
Jerseys: I like the move to the UCLA-style stripes. They have a long history in New England's uniforms, and this striping with the modern colors is a nice medium between the older brands and the modern one. The lack of numbers on the sleeve caps in favor of the Flying Elvis irritates me, but that's a minor flaw. Red as the prominent color in the stripes works well with the the facemask, and the bright red contrasts nicely with the navy jersey. Red/navy/red also looks good on the white jersey. As someone with experience in broadcasting, I dislike an aspect of the uniform meant to make the lives of fans and broadcasters easier being stripped from the uniform, but aesthetically there is little difference. The logo does look good there, although it's repetitive with the logo on the helmet. I'm glad they kept the double outline with the numbers. I've always like the look of white outlined by grey and red. Replacing the white outline with a grey one on the white jersey was a good move for color balance and consistency, and it's one that should've been made for the white jerseys of the original set. I don't agree with the change in font, and I think the previous one was very strong. However, the new one is inoffensive and I have no real issue with it. The jerseys are very strong in my opinion.
Pants: This is where things begin to fall apart. The positive: it appears the pants used at the unveiling were wrong and the actual pants fixed the stripe to match the one on the shoulders. I'm not usually a fan of monochrome, but the navy over navy does look good to me. The matching stripes make it work, and the helmet actually works pretty well with them. However, this set desperately needs a silver set to match. These silver pants should be worn for most of the home games, with the all-navy look being reserved for a few games per season. White over navy should be the primary look on the road, and the silver pants can be used occasionally here as well.
Socks: I really like the new navy socks. The red stripe at the bottom is a really nice touch. But there should be a white pair to be worn on the road with the navy pants. Just take the red/navy/red stripe from the jersey, throw it on a white sock, and call it a day.
Previous home uniform - 8/10. A modern classic with a few flaws.
Previous road uniform - 7/10. A slightly worse version of the home uniform.
Home uniform - 7/10. A fine uniform that needs additional pant options.
Road uniform - 4/10. Far too bottom heavy, with silver and white on top and all navy below the belt. Needs additional sock option.
My fixes here: