Pros: Sound, Battery life, size, power, looks, durability
Cons: UI just OK and while acceptable with even high efficiency IEMs, hiss could be lower
The player, for lack of a better word, is dramatic but not artificially so. More like it has the ability to bring home the soul and intentions of a song. There's a tangibility here that you don't get from other all in one players. Music often has a personal message or story that a performer is trying to relate and it's the hardest thing kit has to do. Call it goose bump factor but it won't show up in specs. This player can transport you there.
It's not perfect. The ui could be more refined (but it's fine), the display larger(but it's fine), quieter (but it's fine) and sonically, it just sounds great in a natural presentation yet dynamic sort of way. It's close enough to just right that there's little to criticize and preference for some other more expensive hi end player would simply be that, a personal preference. It's dynamic, detailed, open, focused and has a unique solidity without sounding hard. It runs forever and plays 24/48 wav files. It will also play FLAC at standard def, aac, wma, mp3 and APE. There's not much here not to like if music is your main goal.
I can get my way around a circuit but really, when I'm listening, I just don't give a crap. I never presume to know more than those that actually create. I think they've stayed with this basic platform and refined it because, A, they know it (and there's a lot to be said for that) and B, they just plain like the way it sounds. So do I.
I can say that judging from comments on comparisons to the V by others, I'm glad I waited. The difference in price seems marginal considering the improvements. Even if small, they seem significant for IEMs. Probably less so for cans.
I've got some Ipod touches, amps with lod, a few Sansa's Rockboxed and not and this is my go to on many fronts but mostly sound as it's tops. It's easily pocket-able and lasts for days. I still have my touch if I want Internet or apps and my clip+ if I just want to clip to my T-shirt etc or am worried I'll drown the player etc. but the Studio has ended my search. It may not be the absolute best player made but it probably is at the price and it has buttons instead of a touchscreen, doesn't cost >$800, is small enough to shirt pocket completely hidden, and lasts for a long, long time. My touch 3 LOD to a custom amp is close but it still costs more and is bulkier than I have any interest to carry. Like many here (some with a lot of experience) it's become my go to player.
I wanted to give the line in a work out so hooked up some original AKG 701s and the lod from an Ipod touch to use the Studio as an amp. It tightened and focused the sound with more slam and bass control while driving the 701s as loud as I could ever use them. The amp stage probably adds around 6db to 10 db of gain full up. I couldn't get it to clip on the AKGs. Maxed, the volume was just bearable for a short time to test. If you don't know these 701s, they're notoriously hard to drive cans and this drove them well.
On it's own, there's not enough gain to play the AKGs very loud but these are the extreme and the amp is plenty strong given enough signal at the line input side. I'm sure it will be fine as is for most cans as well.