Likes
This hauling device is small, compact, and durable. I have used it on a bunch of big walls and never managed to wear down the teeth in any noticeable way. This is the lightest big wall hauler we know of. Since I like all things light, I now use this for almost all my big wall ascents. One great thing about this device is you can haul with just one ascender (you don't need an extra one to catch the rope). I just attach one Petzl Ascension Ascender and you are good to go.
Non Big Wall Applications
This climbing pulley helped revolutionize Yosemite big wall free climbing. Free climbers used to beg and bribe their friends for the tedious job of belaying for hours on end while they worked out the crux moves. The Mini Traxion let them go solo. Now, climbers will hike to the top of the wall, rappel down, fix lines, and then work moves while on self-belay with a Mini Traxion. Only after they have the moves dialed will they come back with a belayer for the redpoint. This is how most hard big wall first free ascents and many repeats are now done.
In addition, this device is very handy at the crag. Can't find a partner? No problem, just fix a climbing rope from the top of the crag and self belay. It is true that self-belaying is not new, and there have been many devices out for years. But the Mini Traxion started a revolution because it is so lightweight, compact, simple, and easy to use. I have used this a lot when I just want to go get a quick workout at my local crag and don't want to track down a partner.
As mentioned in the intro to this review, we now prefer the Micro Traxion over the Mini Traxion.
Here is a SuperTopo Forum Thread about using the Mini Traxion
WARNING: Self-belaying is much different than belaying with a partner. There are many more things that can go wrong. So make sure you study the Petzl web site on how to use this device and also get expert instruction.
Dislikes
This device uses a very small diameter pulley: the smaller and lighter Micro Traxion has a bigger pulley. If your load is under 75 pounds, this device works great. However, if your load is over 75 pounds, you will wish you had a bigger pulley like that on the Pro Traxion or Waul Hauler. If you are just doing a few big walls, this device is expensive. Lastly, because of the big diameter clip in point, you need to make sure you have a special pear or oval-shaped locking carabiner like the Petzl Attache or Petzl OK.
Best Application
I bring this on any wall that I'm on for two nights or less. If I am going to be on a wall any longer, I'll bring a device with a bigger pulley like the Rock Exotica Waul Hauler or Petzl Pro Traxion.
Value
At $85, this device is expensive. If you are going to use it a ton, then the price doesn't matter so much. However, if you are not sure how many walls you are going to climb or how much you will use it at the crag, you might want to try it out first.