A very well balanced level IMO, there's some very clear logic as to what needs to happen, and there's some basic optimization to get yourself to the solution.
I have sneaking suspicion that there are multiple solutions to this, because that felt way too easy (granted, not trivial, but the first thing I tried worked) for a level that looks this intimidating (this has 4 holes, levels with 2-3 holes have given me trouble).
Insights