There are 2 obstacles to go through: the first one should not be a problem because it's a little bit of (easy) dexterity. The real challenge is the second obstacles (the 2 big marbles), because dexterity will be useless....!!
The solution is not the same as for R2D2, but I would say that they have some common points: solving one can help to have ideas on solving the other. Whereas R2D2 has 2 different solutions, this one has only one, but a nice one, of course! I would say that it's moderately difficult and you will have to think outside the box to solve it :-)
Like the other puzzles from Roger D, the trick is hard to find and when found it's not so difficult to repeat it again and again. It makes it a very nice (and collectible) puzzle to own!!
A puzzle for you: why has Roger D chosen this name for the puzzle?...