This little pack sure packs a big punch. With its well thought out features, the Deuter Speed Lite brings home strong scores for its ability to transition through a vast amount of activities.
Performance Comparison
The Deuter Speed Lite works well for day hikes, as well as most day-long activities, like mountain biking or climbing. It just doesn't stand out in any one way, in a field of excellent products.

For day hiking essentials, the relatively low volume of the Deuter Speed Lite 20 holds all you need.
Comfort
For such a small pack, the Speed Lite has a well-cushioned back panel and shoulder straps. Though it may not provide as much ventilation as suspended-mesh back panels, its flexible fit remains comfortable and stable across the board for several torso sizes.

The Deuter on our 5'10" lead test editor, Jed Porter.
Photo: Jed Porter
When filled with a heavy rain jacket, group med kit, water, snacks, headlamp, and a few other necessities, the Speed Lite proved to be quite comfortable.
Weight
The Deuter Speed Lite has a decent weight to volume ratio of 0.94 oz/L. It has more amenities than similar packs, including a minimal frame structure with padded back paneling and shoulder straps, which add a little bit of weight to this pack. This weight-class of backpacks are great for traveling and work well as personal items, or can compress and fit in your luggage or backpacking pack.
Versatility
This is an essentials-only pack. It is perfect for running the Grand Canyon from rim-to-rim or summiting a multi-pitch climb.
It's small enough to take the place of a hydration specific pack, as well as being compressible and packable enough to accompany you on your next backpacking venture. There are a few outside lashing options to accommodate extras, such as your ice axe, trekking poles, and helmet. These lashing options made it a little more versatile compared to some of them minimalist packs we tested

Upon removing their innovative and versatile signature compression strap system, Deuter has lightened the Speed Lite 20 but somewhat decreased its utility. This is the latest version. Overall, we prefer the older version just a little bit.
Photo: Jed Porter
Ease of Use
This is a pretty simple pack with just the right amount of handy bells and whistles. Though slightly less featured than some packs, it still performs just as well.
It not only held all the essentials for our pack test, but it held a 13-inch laptop (without any room to spare).
For 2018 Deuter changed the compression strap configuration. Versions of this pack from the recent past had very useful side straps. There was a pair of them and they could be extended all the way across the pack to lash skis, an ice axe, or a tripod, while still maintaining the compression feature. The latest pack we tested has just one pair of straps that do not work as well or with the same versatility.
One of the drawbacks of this pack is the thin hip belt, which really only aids in some stability as opposed to carrying load on the hips. However, it can also be removed.

With small packs it is sometimes difficult to distinguish carrying comfort. Small loads don't tax the carrying system like larger loads do. To really test these packs we loaded them down with inordinately dense loads and hiked on rugged terrain. With more than you'd ever really carry in it, the Deuter Speed Lite demonstrates its sophisticated shoulder straps and back panel.
Photo: Jed Porter
The size of this pack is both a blessing and a curse, and you should be fully aware of your needs, coupled with the capabilities of the Speed Lite. If you're looking for a pack that is capable of holding a multitude of layers and gear, this is probably not the pack for you. Yet, if you're looking for something on light and fast days for trail running, multi-pitch climbing, and peak bagging then it says it all in its name; the Speed Lite is the pack for you.
Durability
Within the duration that we used and abused this pack, it proved to be quite durable. It protected camera equipment while dirt biking around the Utah desert. The zippers seal incredibly well; however, one thing to be aware of is that the buckles are Deuter's proprietary design. This means that when one breaks, it may be difficult and complicated to replace.

All the tested 2018 Day Packs. Clockwise from upper left: Arc Teryx Brize, Gregory Zulu, CamelBak Fourteener, Top Pick Mountain Hardwear Scrambler, Deuter Speed Lite, REI Coop Flash 22.
Photo: Jed Porter
Value
This pack is a great deal. It has more features than some of our heavier packs and with extra lashing and stow options, it can carry just as much.
Conclusion
The Deuter Speed Lite 20 is your basic day pack, with a few features that set it apart. Our only wish is that Deuter kept their signature strap system on this small pack.

For comparison, since we have tested it, reference it here, and in some ways prefer its design, this is one configuration of the strapping system of an older version of the Deuter Speed Lite 20.