Imagine the GR07 with a better refined and slightly more prominent treble, with the bass quantity, weight, and rumble toned down slightly. With that said, I suggest bassheads to look away (why would you be looking at a TWFK in the first place?). The bass is well controlled and will show up when called for, though obviously not enough to satisfy a basshead, but is adequate for me personally. In terms of what genres the GR01s can handle, they are like the GR07s, in that they can handle basically any genre you throw at them; but I’d still prefer to avoid any bass-heavy genres as the quantity won’t suffice, although the bass does extend deep and has good punch.
 
I wouldn’t consider the GR01 as an upgrade from the GR07 although it is better in its technical ability. I regard it to be as a complement in the sense that if I want to listen to bass-heavier music, I can rely on the GR07, and switch to the GR01 if the treblehead (no that doesn’t mean I’m a treblehead) within me craves sparkle.
 
To sum up its sound signature, the GR01s are quite natural with forward vocals, and with slight bias towards the higher frequencies.
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These were purchased from LendMeURears for $190SGD (approx. $150USD). Normal price is $260SGD (approx. $206USD)
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These are amazing IEMs for the price. It is a balanced IEM and isnt lacking across the spectrum. They can handle pretty much every genre you put through these.
The bass on these is excellent, it rumbles down deep, while being very quick and tight. But the main thing which I love about the bass on these is the 'weight'. When the track calls for it these really do move a whole lot of air and slam it against your ear drums.
As for the midrage, I would say it is neutral, but on some tracks the mids are somewhat warm. With that said.. I'm not sure if the mids are actually warm, or the IEM is just neutral and reproducing warm mids...
The vocals on these are amazing as well. It is very intimate and sweet. These really do make vocals come alive and are also (very) forward (T.V. Carpio's cover of I Want to Hold Your Hand from the Across the Universe OST).
For the treble, I'd just like to say that it doesn't contain enough sparkle to satisfy any treblehead. Despite that, these still contain enough sparkle and detail to satisfy my needs.
Instrument separation on these are also great. I can just 'lock onto' an instrument and it seems like it's the only one playing. A funny remark made by a friend of mine (who is just your typical consumer) told me that he didn't like them because all the instruments playing is all "separated" and not "playing together". (I think he likes to have zero separation and to have a tiny soundstage) 
The only con I can think of is the sibilance. Every lyric that has an 's', (and 'd' and 'th') on some recordings are unbearable. A good example of this would be the song Heartquake! by Sienna Skies.
The only remedy for this is to burn them in for 100 hours. After you hit that mark there may still be some sibilance but they will eventually be non-existant (I have put through around 450 hours through mine). 
 
I am VERY happy with my GR07s! 
 
Here's a list of some of the songs I used to test out my GR07s (all songs are lossless or high quality lossy MP3/AAC):
Perfect Future - Make Fun
Perfect Future - Colonization
Sienna Skies - Heartquake!
T.V. Carpio - I Want to Hold Your Hand [Across the Universe OST]
Joe Anderson & Salma Hayek - Happiness is a Warm Gun [Across the Universe OST]
Papa Roach - Getting Away With Murder
Versailles - Silent Knight
Uppermost - Born Limitless
Uppermost - Satellite
Morgan Page - The Longest Road (Deadmau5 Vocal Remix)
with some classical here and there.
 
 
 

I bought these Jays while looking for a good entry-level IEM to upgrade from the ibuds.
 
These IEMs, to my ears, sounded V-shaped. Elevated bass with aggressive treble.
I could not stand listening to some tracks with these on because of the sibilance.
The flat cable is very worrying for me, especially how it is terminated. The plug just seems like it is just waiting to fail because it just looks, and feels, very cheap and fragile.
Microphonics is another major issue. There is a lot of microphonics, and trying to wear these over-the-ear to try and solve the problem isn't viable, as I couldn't even do it. The cables just wanted to straighten out and the IEMs kept popping out.
 
For $60 USD I really wouldn't suggest these, as now there are much better choices out there in the market. The only reason which would make me suggest these is if that person who wants to wear eye-candy.
But as an upgrade from the ibuds, I can't see anything wrong about that.