They put a lot of thought into this sleeping bag and I am more than happy to benefit from it. I wish I could afford to try out their zero degree bag as well and see how it compares, but since I only had enough money for one, I went with the -35. Here are my thoughts:

-It's heavy. Using a baggage scale, I weighed mine at 16.4 pounds in its duffel bag stuff sack.

-It is warm. I sleep like an icicle, but I was incredibly warm and comfortable in this.

-You can't put two of these in a two person tent. Normal sleeping bags? Yes, absolutely. This? No. This monster is very wide, so putting two in is just asking for you and your buddy to get stuck on each other's bags. You'll be frustrated and unhappy. Get a three person tent if you're going to have two of this same bag in there.

-The duffel is great. Unfortunately, one of the handles on mine already started to tear, which makes me worry that the stitching wasn't very high quality, but hopefully it stays at just that one trouble spot because otherwise, this is a great duffel. The sleeping bag actually goes right back into it very nicely (since the bag has built-in compression straps). The duffel has a strap at one end to carry it with or tug on if you've stacked this in with your other gear, and it's also got the normal carrying hand-straps. The zipper goes all the way down around one end, making it incredibly easy to get the bag back in.

-The bag is almost too long for your average two-person tent, so be aware that in rain or snow you may need to tuck the end of it up a bit to make sure you're not pressing it on the tent walls.

-Comfortable. Comfortable. Holy crap, this is comfortable. I love the inside fabric. The outside fabric is a little bit unpleasant feeling (it's very rough and feels a little on the low end of quality to be honest, I was hoping for something a little more smooth), but since you're going to spend most of your time inside the sleeping bag, it really doesn't matter too much. The interior fabric is great, the bag is comfortable, you'll be happy.

-The zippered pouches are great, both on the sleeping bag and duffel. Nice touch!

-The sleeping bag zipper feels high quality and didn't snag yet.

-If you're fat? You'll like this bag. To be brutally honest, fat people often struggle with feeling comfortable rather than constricted in a lot of mummy sacks, and honestly I don't even like the average width of non-mummy sacks because I like to be able to worm around, stretch, put my arms out easily, et cetera. I'm fat. This? This was great. I could sleep pretty much sprawled out in it, I was so warm that I could put my bare arms stretched out and not feel chilled, I could curl up in a ball, or on my side, whatever I wanted, and being fat was not a problem in this bag.

This is definitely only for car camping, or for being towed in on a sled as some others have suggested, but all in all it's a very comfortable, pleasant sleeping bag. It's huge and takes up a LOT of storage space, but I definitely recommend the bag to anyone who does a lot of car camping in cold conditions. Thanks, Teton Sports, you've just made my car camping future a lot brighter, or at least a lot warmer. My last sleeping bag was a down backpacking one that I had used for years and beaten up pretty badly because it got so much use, and at this point it was just really not insulating me at all anymore, had become a summer bag and nothing else, but gsdhgjdfhd. Yep. Keysmashing time. I'm happy.

I've used this bag many times to sleep in the back of my truck while on snowboarding trips. It has kept me completely warm, even when the temperature dropped to -2º F overnight at about 8000 feet. The zipper is easy to use and doesn't get stuck. It has 2 cinch drawstrings around the hood to control the size of the opening. It's spacious enough inside that I can side-sleep and bend my legs without feeling constricted. My sleeping pad got a hole and deflated one night, but the insulation in this bag is so thick that I was still pretty comfortable without the pad. As others have mentioned, if the temperature is above +40º F you'll probably be TOO warm, it really is meant for winter conditions.

I bought it to stay warm. Took it out in 28 degree temperatures and it kept me warm as I expected. I don't know if it would still keep me warm in zero or below temps and I will probably never find out.

A few cons:

The inside pocket isn't big enough for an iPhone 7. Forget any Samsung's or iPhone pluses. This is important because when camping in cold temperatures, cell phones either shut down or don't work properly. This caused me to have an issue with an early morning alarm not going off to wake me up.

Not really a bad thing because I expected it, but this thing is huge. Packs bigger than my 10 person tent. Bonus is that the storage bag is also huge and there's is no problem stuffing it in like other less expensive bags. This is definitely not a "pack-in" bag so know what you are buying.

Huge and comfortable bag.
I took this out on a weekend with moderate winds and lows of 27F - the water bottle in my tent formed ice, but I didn't!
Extremely nice place to be when it's cold and windy. Very roomy, even for a guy just under 6' and 200#. My dog actually got cold and climbed in as well, so I can say with certainty that it will hold one man and an aussie cattle dog.
I bought my wife the Outfitter XXL, so I'll have her write up her experiences with that version.

This is about as good a sleeping bag as you can ever buy!.....yeah it's heavy..... But I camp in the snow often... And them light weight pack ones don't cut it, even if they are rated to the same temp.... This bag is warm:) .....when I'm pack boarding I don't mind the 10 extra pounds and I sleep good, while I watch too many friends with their high tech ultra lightweight bags suffer all night..... this sleeping bag made me comfortable all week in the Boy Scouts when we camped in snow caves for a high mountain winter jamboree we attended several times....And the funny thing is half the time I camp or go hunting in the winter we camp off some road and don't have to pack, so why not have a warm sleeping bag:)..... Lightweight bags only weigh 10 or so lbs less, yeah 10 lbs seems like a lot, but it's worth it to me when I go ice fishing at a high mountain lake to sleep good that night......... Only warning..... With any sleeping bag if you spike camp without a tent, bring a tarp and keep yourself dry while sleep:)