I used this recently for my first (and probably last!) 100+ mile run/walk in 48 hrs. I used it before the race to tape likely blister areas on my feet, as well as on shoulders and around the waist where a backpack might rub. It is also very good for the all important nipples as these can seriously hurt after a few miles running.
It performed superbly well. One foot did 105 miles with no blisters, the other did get 2 but that was largely due to my knee seizing on that side & having to walk with a strange gait for 50+ miles and failing to re-tape it to meet the new requirements ( a lot of sideways movement on the heel). The tape stuck on really well, even though I had erroneously rubbed some lube onto some areas beforehand. I only had to re-tape one bit, and that was because I had missed a section that was beginning to rub. To be fair, this was in dry conditions and it only had to cope with sweat. In heavy rain, perhaps it would come loose faster.
It was easy enough to remove after a soak in a warm bath, and did a first-class job of preventing blisters under tough conditions. For the record, I recommend taping all round all toes, sides of the feet where they rub, backs of heels, and any other points that look likely to rub. During a long run, as soon as you can feel a 'hot spot' developing, tape it up and you should be fine.
The tape is not easily torn with just your fingers, but biting the edge with a tooth and ripping from that works fine, so scissors not essential if you are travelling light. I found the 3.8cm size most helpful for toes / feet, but it would be worth having the wider size for shoulders if required, as it saves having to do quite so much taping. It is also good as general first-aid tape for securing wound dressings, or strapping joints. It is significantly cheaper than moleskin and hi-tech blister plasters, and I would always use this as a preventative measure in preference to moleskin. It also works well to tape over small blisters before they have got too large. Once you have a sizeable blister, I'm not sure if you are better off using a 'Compeed' type, or draining it and then strapping generously with tape. I think the tape would work well for the remaining duration of the walk, but you may be better off switching to Compeed later for the healing stage. If you're looking to minimise weight or cost, I think you would be fine with just the tape.
Prevention is always better than cure, and this did a superb job of preventing blisters. To be able to do 100+ miles in under 2 days with virtually no blisters or raw skin is a very good result, so highly recommended.