The Tena Pull up line are not too bad, at least as far as adult disposable pull ups in general go.
Pull ups are usually very poor in performance compared to a taped brief, They hold a lot less and are more prone to leaks but also are usually thinner and more discreet for those who only need low capacity daily wear without the bulk. Tena are up near the top of the list but not the best (at least as far as those accessible in the UK go).
As far as I can tell the difference between the normal "pants" and the active fit ones is basically a slightly improved ADL (acquisition and distribution layer) that pulls urine away from the skin better and faster leaving you feeling dryer, as well as a more breathable waterproof outer layer.
This can be a blessing and a curse, Better ADL is always a good thing for skin health and speed of absorption but also can mean if you feel dryer you may underestimate how wet the pull up is so you pee more and leak. Also by making the outer more breathable means the waterproof laminate is thinner and the material as a whole is more porous so while it does promote healthier skin by allowing better airflow it can also mean greater chance for vapor/moisture to seep through onto your clothing.
Tena have two main lines beside the base for their products with the main basic difference being the Pro skin has the more breathable cloth feel outer while the Active fit is plastic outer layer and cut slightly trimmer to fit more like underpants allowing higher mobility.