I do not see the purpose of the ipad pro as of 2015, for most consumers. In winter 2016 or spring summer 2017 it may be different. Notice the keywords most, and consumer.
Current very little software is ready for stylus input and this will also be true for the next year or so. Now there are some exceptions to this like microsoft office with one note and some of the adobe programs but besides that you just have a bigger ipad.
Given time though the Ipad Pro will be amazing but it takes time for developers to actually make software or to add features.
Yet the ipad pro cost $900 to $1100. $800 for tablet, $100 for pencil/stylus, $170 for the keyboard (which looks horrible to type on, but we will see) and even more if 32 storage is not enough for you, or you want lte.
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All to run ipad apps in a bigger form factor. Eventually lots of stylus/pencil apps will appear but since it is going to take 12 months or so, why don't you wait for the massive improved ipad pro 2 or 3, since you will barely being able to use your stylus today.
Ipad Air 2 can also do split screen, and is extremely fast for a tablet cost $500, is it really worth it to get the ipad pro in 2015 for $400 to $600 more? Especially when the silicon is advancing so much in a year's time with the apple products?