I owned a surface pro 3 and wanted to love it, but god, it was just awful. Short battery life, crappy eMMC-based storage, weird foldable keyboard you couldn't use on your lap, display that wasn't so bright, rarely if ever came out of suspend properly, the pen required two different kinds of battery (!?) and perhaps my personal favorite, the display sometimes rotated sideways and wouldn't de-rotate.
Pretty sure the iPad will have zero of these problems when it ships, and that makes all the difference, even if it's two years "late".