This 3x3x5 is fully functional. It is cubic, meaning that it doesn't change shape as you solve it. It's about the same size as a 3x3x3 cube and looks and feels like the top and bottom layers have been sliced in half to make the extra layers. The thin layers behave a bit like a bandaged cube when the top and bottom layers are not solved.
There are a few possible approaches to solving the puzzle. You can solve the top and bottom layers first and then solve the 3 remaining layers mixing domino and cube methods here and there.
You can also solve the inner 3x3x3 part of the puzzle first and then aim for the outside section.
This is a lovely puzzle - it can be fun working out how puzzles of different dimensions can be solved in sections using methods from other puzzles.