I seem to be a little bit of a different user in that my SP3 is actually a DESKTOP replacement.
I never made the full-time jump to a laptop that most people did, I've always preferred a good, self-built and tuned desktop. The one I replaced was a few years old but was still doing the job for me 98% of the time (it was a powerhouse when I put it together). But, I definitely loved the idea of "taking it all with me", as it were, that a laptop offers, and I was a bit envious of some of the new tech available besides.
The SP3 was a good choice to replace my desktop as well as my sometimes-used laptop it seemed... the power of my desktop in an ultra-portable package (that just HAPPENS to be a tablet too, which is pretty much a BIG added bonus). I had an initial problem that I'm still not sure of the root cause of that resulted in me having to do a full reset after spending 3 days installing all my software... that sucked... I was actually worried at that point that I might have made a bad mistake with the purchase... but after the reset everything has been working flawlessly since.
I currently have two external monitors running off of it (I'm a big multi-user proponent) with the Surface itself replacing the third I used to have, plus of course a proper keyboard and mouse. The biggest issue I've had is that hibernation causes the monitor resolutions to get messed up and I have to reboot to restore them. That's a pain. I've just turned hibernation off when plugged in now and it's all good (not happy about wasting the power of course... I may take to shutting down overnight, not sure yet). Otherwise, I don't think I really have anything to complain about.
I'm not a big-time gamer, but my gaming needs are being met just fine with this thing. I still play the original Halo, and Postal 2, and I can jack them almost all the way up setting-wise and have a good experience (after activating Hyper-V to get access to performance mode at least). Speaking of which, Hyper-V is actually working quite well for me, which deals with the other problem I had: VMWare wouldn't work with Hyper-V installed... so it's either VMWare but no performance mode or performance mode but no VMWare. While I still think VMWare is better than Hyper-V, it's good enough to make that choice easy.
I'm primarily a developer and it more than meets all my needs in that department. I was a bit worried about "only" having 8Gb RAM, but from experience I knew that would be sufficient, though with not much headroom, and that seems to be the case. No out of memory situations yet and I don't really expect any, though I do kind of worry about down the road a bit. We'll see. The SSD is a bit cramped I have to say, but a 64Gb uSD card more or less solves that problem (and I have an external 1Tb drive to fall back on if need be too).
I still find myself using my Nexus 7 when I'm sitting on the couch though frankly... it's still more convenient in that role then the SP3 is (that kind of quick-access, "take it with me into the bathroom" role- come on, you know we all do it!)... but it's so much nicer to be able to grab the SP3 when I have to go wait for the kids to get out of school and still be able to do REAL work
No more synching stuff later, just pick up right where I left off. That's sweet! Sure, it's not unique to the SP3, but I think the form factor makes it much nicer. I can't wait for the dock to be released though... I don't like plugging and unplugging cables in all the time.
So yeah, I'm very happy with the purchase, even though it was quite a hefty outlay (256Gb i5 + TypeCover + MS service plan + DP hub + DVI-> DP adapters + 64Gb uSD) I think it's proving well worth it... my "new desktop" performs no worse than my previous desktop and actually benchmarks quite a bit better so it's probably performing better real-world too, though the difference isn't huge if so. All in all, good decision