[Sprint Samsung Galaxy S III] imaconeheadXD:
Well here's my impressions after about a month with the S5:

Performance: The S5 is definitely a lot snapper than the S3 because of the much newer processor, and the new graphics chip has been great with no more lags in games (like Temple Run).

Multitasking: The 2 gigs ram that the S5 comes with are more than enough to run a ton of applications, because the newer kernel and Android version are able to free memory much more effectively than before, I've found no lag when switching between ~20 applications.

Features: Even though not much was added from the S4 to S5, you still get everything that was on the S4 like the IR blaster and Air View, which are big upgrades from the S3. Download booster and wifi calling are currently disabled by Sprint, but we have some devs working on bringing them back.

Development: So far there are only a couple devs with their work out for the Sprint S5, but this time Samsung made the international and US carriers the same chipset and such. Being that Sprint markets this as a world phone (capable of international GSM) so we could edit the APN'S, [MENTION=5697562]RevelationOmega[/MENTION] is working on a flashable zip that would allow Sprint users to flash any international ROM for the S5 and still have working data, which opens up many more ROM choices.

Battery: Battery on this phone has been pretty good and lasts me about 11 hours of (daily) heavy use, with light use I was able to go 23 hours with 5 1/2 hours on screen time on stock rom stock kernel, rooted and greenified.

Screen: Just look it up on literally any review, the S5 screen is the best in a smartphone, period. Colors are great, and goes both extremely bright and extremely dim. Autobrightness is actually usable on stock (instead of needing Lux).

Camera: LOVE IT. The 16MP isocell sensor is just great (at least in the light) and takes extremely detailed pictures. The refocus effect is very cool when it works, but most shots I try to use it the "subject is not detected" error toast comes up and it won't apply the effect. For some sample pictures, go to photos.teaminnov8.us and go to the S5 test folder. Low light performance is just average, and it does become fuzzy and pixelated.

Finger Scanner: I've had no issues with it, sometimes it takes 3-4 swipes to make it work but most times for me it works on the first try, I do use it as my default lock.

And finally almost over, there are a couple of things that I had issue with. First, know that because this is "Sprint Spark" capable, you cannot use data while on a call unless you're using wifi. Instead you do get upgraded speeds in Spark enabled areas. This is fairly good, but I've found that you must be in very specific areas (at least in Queens, NYC), literally for me within a 10 foot radius of a specific light post on the street I get speeds around 52 MBPS, and if I go farther than that I drop to about 3 MBPS, still on Sprint 4G. Also, smart pause and air view seem to be finicky most of the time to the point where it's just easier to leave them off to avoid problems, so just be aware.

That's basically it, hope this helps! I do recommend upgrading to it as a final verdict. If you have any other more specific questions, feel free to PM me. Now back to your regularly scheduled MOAR!