You either hate Jammies or love them. I love them. I used tape when I was learning to climb crack, but my hands still hurt because of my poor technique. I bought the Jammies as a training aid to better protect my hands and to be more comfortable as I was focusing on learning technique. I quickly came to depend on the Jammies, and eventually came to love them. They take only a moment to take on and off, as opposed to five or ten minutes to tape your hands. The thick rubber is as grippy as climbing shoes, and they help cushion the backs of your hands by spreading the forces across a broader surface area. The only detraction that I have found is when cracks transition from hand to finger. The extra couple millimeters of rubber thickness can make the difference between getting your fingers in the crack down to the third nuckle or only the second. I am only a 5.9/5.10 climber so I have not be hindered by this limitation. The Jammies have given me the confidence to climb cracks when I otherwise might have chickened-out.
I had these shipped to the UK from the US as UK retailers seem to blank them - I think it's because climbers here regard them as cheating as they make gnarly gritstone jamming cracks a lot easier. That's true and you may have to think twice before bragging about grades you have climbed using these. They do however make that type of route a lot more enjoyable and for me that's what it's all about. hand jams stick in all orientations with little or no pain at all - no taping and subsequent hand waxing, what a relief !! I can't comment on durability as I've only used them twice by they seem sturdy enough. I have to say that despite having large hands I seem to fare better with the medium sized pair I had shipped. For the large pair to fit snuggly you'd have to have truly giant hands.
When I first got these - I immediately thought about the stitches being exposed to the sharp rock out at Josh and the High Desert - so I put a bead of SeamGrip over all of the stitching (this stuff is bomber) - and they've lasted at least 20 crack climbs without a sign of peeling or the stitches being exposed... Love this product - but without doing this the stitch will likely deteriorate as it has to other reviewers...
The rubber is only on the back of the hand when wearing "Hand Jammies". It is secured by the wrist strap and elastic finger loops leaving the palm open. Not a problem but should be included in the product description. I bought these for my wife but also enjoy saving skin and tape by using these.
These worked really well for me in #2 cam sized cracks, which are big for my small hands. I only wish they made them in XS. They even seem to have improved my crack climbing technique when I'm not wearing them.
Jammies are great... definitely improved my crack climbing. In some locales these are considered "aid climbing." I'm OK with that because I'm getting some experience with crack climbing without repeatedly losing the skin on the back of my hands.
I really like hand jammies for climbing cracks at the gym to work on technique. You don't have to fuss with the time and effort needed for taping up. However, the single stiching on the velcro straps and along the bottom edge is insufficient, and mine have fallen apart after only about 10 days of gym climbing. Two of the four straps fell off (not overtightened) and the rubber along the bottom near the cuff is separating. I'm hoping for a replacement, but we'll see.
Hand Jammies do technically work, in that they protect the backs of your hand and are easy to put on and remove. The craftsmanship and/or design is poor, however. Mine developed a tear at the stitching after two climbs, then just tore in half and fell apart in the middle of the third climb. As my partner wryly said afterward, $35 can buy a lot of tape.