Lots of internal space for the weight and fast, reasonably easy setup, but poor ventilation (even with the hyped Drywall breathable fabric), lots of condensation, a floor that wets out and vestibules so small they are pointless, leaves the Sputnik less than ideal. Too bad, as the over-all design is intriguing. I say avoid unless you can nab one for $150 or less. The North Face Phoenix has a much better design to take advantage of the Drywall fabric technology, and if I had to choose, I'd spend the extra money and carry the extra pound over the Sputnik. Plus, you'd get two legitimate doors and vestibules you can actually use with the Phoenix.
Let me say straight up this is a great pack. I heard from a local outfitter that the Alteo packs from TNF were designed by the same guy who created the first Atmos packs for Osprey. If that is indeed correct, I can say without a doubt he easily out did his original designs. Feels quite a bit more comfortable than my older Atmos 50, and certainly more comfortable (to this reviewer) than the current Osprey Atmos and Exos packs. Suspension is more robust, can hold more weight and provides more back ventilation than those other packs as well. Lots of thoughtful features, including real honest to goodness side pockets you can use when the pack is full (gosh... imagine that!) and my favorite - access to the main pack via the top AND the side. This is a huge plus because now you can easily get your sleeping bag into the bottom of the pack (often the bane of "trampoline-style" backpacks) and then just zip up the side and proceed to pack as normal via the top. Very effective stuff-it pocket on the back for a rain jacket or whatever, plenty of lash points to secure more gear and straps at the bottom attach a tent or sleeping pad.
Another thing that make this pack special is that for a 35 liter pack (2100 cubic inches), it holds about as much as any 50 liter (3000 cubic inches) I've used in the past. In fact, my original intent was to purchase a 50 liter pack (looked at the Alteo 50 as well - a superb bag as well) to supplement my 65+ liter pack, but after seeing the potential of this 35 liter "little backpack that could", decided to give it a try with my gear at home.
Much to my happiness, it swallowed up all my gear for a 2+ day late summer/early fall style trip, including my 15 degree bag down bag (summer bag wasn't available at the time) which packs reasonably small, but still more volume than your typical summer sack, + 100 liters of water in the hydration sleeve, treking poles, and Ice axe (just for fun), single-person tent, air-pad, food, water filter, clothes, etc. There was still room to fill up another sack of food, clothes, or gear under the top lid as well. By the time I was done, it was stuffed and was holding more than it might have been designed for, but still it carried very nicely. Didn't have that "I'm being pulled backwards" feeling I have gotten with trampoline style packs in the past, due to their tendency to pull the center of gravity away from your back. Not sure how TNF accomplishes this, as there is still plenty of room between your back and the frame sheet for exceptional ventilation, but they did.
One thing worth pointing out is that the Alteo 35 comes in a "one-size fits all" configuration which might be problematic for some folks who are on the fringe ends of the torso spectrum. I'm a 19" torso so I fall right into the happy middle. There seems plenty of adjustment available, though, so the concern might be mute. Beyond that, the only thing I would change would to make the top lid fully floating for greater packing flexibility, and then put quick-release buckles on the bottom sleeping pad/tent attachment loops. That is about it. Seems a great pack. If it holds up over the long-haul (fabrics seem plenty tough yet still light-weight), TNF will have themselves a serious winner with the Alteo line. Glad I purchased it. FYI... I will try to post some pictures later this week, and yes - I got the Venom Yellow and it looks better (a bit more sedate) in person than in pix.