I have a bunch of Lumias and a Neo, and I honestly prefer the Neo for several reasons:
1. Samsung devices, for some reason, have the ability to run multiple things in the background and not suffer horrible battery drain. My 925, 920, and 520 cannot.
2. Samsung phones tend to have better heat dispersion. It has never gotten beyond comfortably warm, even from intensive tasks.
3. Larger screen. The Nokia's LCD and AMOLED screens can't be beat, but the Neo has nice ppi and a good size. Its auto brightness is a tad dimmer than the nokias but it's not a deal breaker at all.
4. SD card expansion and removable battery. While not a big deal for some, it's required for me.
However, if you take tons of pictures, the Lumias might be a better choice. The camera on the Neo, however, is not bad in the slightest and they lack the terrible yellow tint that many Lumias have gotten with their firmwares (ALL of my nokia phones have them. Even on a computer its noticeable). Daresay, I think the Neo's camera is quite good. Surpassed my expectations, but that's just me.
However, what is said above is true. Samsung isn't fully 'in the game' right now, and they have not released firmware for WP8.1 yet. Still, I'm running 8.1 GDR 1 and it's working flawlessly, save for a few minor bugs which can be overlooked. Overall, I feel the Neo is a solid device. Got mine off ebay for 130 bucks locked to ATT, I'm sure an international unlocked version won't be much more expensive.