In reply to Sean Kelly:
I have a surface 1 and have used it daily for 18 months both as my tablet and as a portable device that I can take into work, plug into a large screen, hook up to a keyboard and then work away, faster than the desktop PCs all around me. The 3 is going to be even faster and with double the battery life. At home, on a train, on holiday I can manage on the small screen with the clip-on keyboard cover, although I have a proper laptop in my home office for screen heavy tasks.
Any complaints you'll hear about Surface are really complaints about Windows 8, which I quite like actually but I understand why some don't.
Don't buy one without a keyboard cover and I highly recommend getting a (cheap £60ish) big fixed screen to plug it into for complex spreadsheets, desktop publishing etc.