I actually like this better than Isaac. The double "a" seems a little bizzare to me. I'm usually not one for modern names, but if anything, this looks more like it would be the "correct" version. But that's just my opinion.
With this spelling, the name should be pronounced ''I-sak'', not ''IE-zak''. If you really want to use this rather ugly name on your son, spell it the logical way.