Although the book is long, you don't have to read all of it. Chittick is not arguing a thesis, but presenting Ibn Arabi's view on a variety of subjects which are fundamentally rooted in a non-dualistic cosmology where only Allah 'is'. You can read just the introduction of the work (where Chittick gives a bare-bones sketch of the Shaikh's worldview) and then start plugging away from the various passages at your own convenience.
In my opinion, SPK is better than Chittick's more recent THE SELF DISCLOSURE OF GOD which is too technical and requires quite a bit of familiarity with Ibn Arabi in particular and sufism in general.