If we compare these to MiMH they seem great! I had a look at this site...
The UBC44106102 at the top of the list is rated at 3.8 V, has a 3800 mAh capacity and weighs 108 g.
From the energizer site, their AA 1.2 V, 1600 mAh battery weighs 27 g, so 4 of these AAs weigh the same as one of the above polymer batteries.
The capacity (in mAh) of both batteries is stated for a discharge of 0.2C.
Total energy stored in one UBC44106102 is 14.4 Wh.
Total energy stored in 4 AAs is 7.68 Wh, i.e., (4 * 1.2 * 1600).
So the polymer is about twice the energy density of the NiMH. About the same as an alkaline! (Pelu?)
The max discharge rate of the polymer is 2C, which seems to be a bit less than NiMH which is usually 3C (I think). But since the polymer is twice the capacity, this means the polymer can put out a higher max current than the NiMH.
Cool