I have been using the surface pro for about a week now, and it's been brilliant.
I'm not an Apple fan, so my primary tablet was a Nexus 10, used since the day I first received it (first batch on the first launch). Everything was great with the nexus except for a few things:
1) Things are somewhat smooth, but they're still not fast. At this point it seems like with such high resolutions, the available processors/gpus are just not up to par on the ARM side of the race. The i5 in the pro however, is nearly as snappy as the i5 on my main desktop.
2) Everyday desktop tasks were a pain in the ass. I need to be able to easily search ebay, and post listings on ebay. Not so easy when you need to dig around for previously uploaded images, resize those images, upload to imgur, then to finally post them to ebay.
3) Typing. I hate typing on a touchscreen. Tried it ever since I had my rom'd Kindle Fire, my Nexus 7, and my N10. Never got used to it. But typing on the type cover is perfectly. Hell the touchpad on it beats out my 2008 Lenovo touchpad.
I'm keeping this thing. But, one haswell drops, I will sell this and upgrade.