The barrel was presented by Tony Fisher already on the DCD2008, but luckily he made eight more puzzles of this type for sale.
The puzzle is quite confusing. This is not only because it is shape shifting, but also because the special stickering. Besides orange and red, which are used for top and bottom of the barrel, the round face is stickered with eight different colours.
As a result, the centers of the puzzle (referring to the original 7x7x7) are not covered by one unique, but three colours. The five leftmost and the five rightmost center pieces belong to a different colour group each. This gives the puzzle a slightly higher complexity.
On the other hand, the original edge pieces are only having one colour, which avoids some orientation parity problems and decreases the nominal complexity.
Some center pieces cannot placed at all positions anymore as with the original V-Cube, because their shape has changed and so they are there are pair-wise anti-symmetries now.
So for the two pairs of four identically stickered center pieces there are not four valid positions, but only two over-crossed locations.
The puzzle has more than one solution (regarding the colour scheme, not only identically coloured pieces placed at equivalent locations), because the the rounded corner lines with their adjacent 2nd layer pieces do not have a unique position between the three middle columns.
The mechanism is working very smooth, as the 7x7x7 V-Cube does. Because of the rounded shape especially at the end, when the barrel is nearly solved and in shape again, the twists have to be done very carefil to locate the "horizontal" barrel rings correcly to each other.
Size: "Similar" to a 7x7x7 V-Cube