Advance Pro Updates
Since our test cycle with this Top Pick winner, MSR has tweaked the design a bit. There are now side vents, which can be see in the first photo, below. The second photo shows the model we tested.
Since we haven't tested the model with the updated vents, the review below still tells our account of the previous version.
Hands-On Review of the Advance Pro
The MSR Advance Pro is a bomb-proof bivy tent with a minimal-weight focused design. It's one of the lightest tents in our review and has the smallest interior floor plan, with only 24 square feet in which to lay down. There are not a lot of extras, such as a bug mesh screen on the door.

The Advance Pro is our new Top Pick for the Best Bivy Tent. It is one of the lightest and most compressible models in our review.
Credit: Ian Nicholson
Ease of Set-up
The Advance Pro is the easiest bivy-style tent to set up in our review.
Unlike most 2-3 pole single wall tents, you don't have to crawl inside the tent to set it up. You won't find yourself battling to find pieces of Velcro or plastic twist-ties as the tent blows around in your face.

The Advance Pro was one of the easiest models to pitch in the 3.5 pound category. We did not have to crawl inside it to pitch.
Credit: Ian Nicholson
Instead, simply unfold the poles that are pre-attached in the center, slide one half of each pole into pole sleeves and then clip three plastic tabs to hold the pole in place. Not only was this set-up quick-and-easy, but it was also bomber.

In the previous photo, you can see the pole clips on the front of the tent, and in this photo, you can see the external pole sleeves highlighted by their red fabric.
Credit: Ian Nicholson
Weather and Storm Resistance
This is one of the most stormworthy 2-pole models in our review. If we were expecting to get blasted by strong winds or heavy snow, then this is the bivy tent we'd lean toward.
The Advance Pro has two poles that cross in an "X," a design that's fairly typical of lightweight bivy tents; in this case, they are always connected using a hubbed design, which adds a great deal of structural integrity. The fabric is pretty robust for a sub three pound tent.

The Advanced Pro gets a ton of its strength from its Easton Syclone composite material poles, which were easily the strongest among bivy-style tents.
Credit: Ian Nicholson
The Advance Pro has six guylines that are reinforced where they attach to the tent, far more so than with other sub four pound models. There is also a seventh reinforced tie-in point, where an additional guyline (or the rope) can be attached to both the tent and the intersection of the poles, adding a tremendous amount of strength.

All of the guy-points are nicely reinforced. The center ones (shown in the photo here), are crucial to maintaining strength and minimize flapping. On most models, they are the most common to tear out, leaving your tent weak and exposed; this is not the case here thanks to the way MSR designed them, reinforcing them from the inside.
Credit: Ian Nicholson

In addition to the guylines, the Advance Pro also sports a reinforced tie-in point at the apex of the tent where you could use your rope or other materials to tie it down if the weather turns grim.
Credit: Ian Nicholson
Weight and Packed Size
With a minimum weight of two pounds 14 ounces, (just the tent itself and nothing else) and a packed weight of three pounds three ounces (packed weight is tent plus guylines, pole bag, and stakes) the Advance Pro is one of the lightest in our review.
The Advance Pro keeps the weight low but maintains its status as one of the most stormworthy tents in our review because of a few factors. It was the only model with two carbon fiber poles that permanently intersect at the peak of the tent. It also has no mesh door and has the smallest floor area.

The Advance Pro offers 24 square feet of living space, one of the smallest in our review.
Credit: Ian Nicholson
Livability and Comfort
At only 24 sq ft of interior floor space, the Advance Pro has the least amount of square footage of any tent in our review. If you are 5'10 or taller, both your head and feet will touch the walls all the time.

There is no mesh bug screen on this tent, which is nice to have in buggy weather. The fabric on this tent is also not particularly breathable, meaning you want to sleep with the door open when the weather and bugs allow.
Credit: Ian Nicholson
While small in square footage, MSR didn't just cut off the length, which our taller testers appreciated. There is only one small vent for ventilation, and the fabric was only okay for breathability. Even with the door left halfway open in the humid air of the North Cascades, we'd see condensation develop with two folks sleeping inside.

The Advance Pro with two 6'1" people sleeping in it. It's a little tight (to say the least) and with the door zipped closed, their heads and feet touch at both ends.
Credit: Ian Nicholson
Durability
The Advance Pro earned a relatively high score for durability. All of its components are solidly made; however, when going so light, you sacrifice a bit on long-term wear, and this tent may not last as long as the beefier 4 season tents in this review.
Adaptability and Versatility
The Advance Pro is not a particularly versatile tent; instead, it offers a very focused design toward creating a strong and weather-resistant design with minimal weight and packed volume. This leaves little room for compromise.
This tent breathes poorly in the rain, features no bug netting, and would be a bummer to hang out in for any length of time.

The Advance Pro's biggest disadvantage is its breathability. There's no bug-netting and only one tiny vent, which won't do much if you're forced to sleep with the front door closed.
Credit: Ian Nicholson
It is best used as an alpine, mountaineering, or ski touring tent, where its minimal weight and packed size, combined with its stormworthy design, will be appreciated.

The Advance Pro has a focused design; while it doesn't work great for a broad spectrum of applications, it's ideal any time you might need a lightweight and compact shelter that can still withstand the elements. Its tiny footprint lets it be pitched anywhere two people stand a chance of laying down.
Credit: Ian Nicholson
Value
The Advance Pro is in line with other similarly designed bivy tents. It's an excellent value for how much storm protection you get for the weight.

The Advance Pro isn't particularly versatile but is fantastic at what it is designed to do, which is to be as light and compact as possible while still offering top-notch storm protection.
Credit: Ian Nicholson
Conclusion
The
MSR Advance Pro is fantastic at what it's designed for - to provide a stormworthy place to sleep while weighing you down as little as possible during the day. It's one of the lightest models in our review, but it's one of the most storm-resistant and weather-proof of the sub-3.5 pound models. It isn't versatile and doesn't even have a bug mesh door, nor is it comfortable to hang out in, but it is light, and it is bomber.