I think you have found a really clever mechanic, the spider jumps are deceptively simple and yet entertaining. I suggest a different key binding for the spider: when you are on the roof, it's odd to press "up" to shoot down, it feels more natural to press "down". This may improve the gameplay.
Also, i you want to add a more action twist, you could add some enemies that walks on ground or roof, and you must block them with the net before moving on the same ground, for an additional layer of challenge.