Pros: Neutral sound signature, good details, great performance for the price, moderate impedance makes them versatile with different sources
Cons: Fit took a while to get right with adjustable nozzles / square housings. Cable guides are bulky and without them the cable sometimes falls off my ears
I've written a full, more detailed review here: Passion For Sound
In summary though, the GR07 MkIIs are a brilliant earphone for the money. The only other IEM which I find comparable for the price is the HiFiMan Re-272 which is now no longer available. The GR07 holds its own against the Re-272s and actually out-performs it in terms of total frequency balance (the GR07 has the bass response that the Re-272 lacks). Of course, if you like more colouration in your sound, you'll probably prefer other IEMs so when I'm saying how great the GR07 is, I'm referring to it as being a great performer for balanced / neutral sound.
The sound the of GR07s is refined, clean and authoritative. They cover all frequencies well and have a nicely defined soundstage presentation. I believe the soundstage improved with burn-in and others have said the same so give them some time before judging them. Also, while discussing burn-in, the treble may be a little hot when their new, but this definitely settles down and although detailed, the GR07s are not a harsh sounding earphone once burned in.
Highs: clean, defined and detailed, but not too bright
Mids: just right - not sweetened, not too creamy, just natural and realistic
Bass: impressive, but natural - plenty of deep impact and rumble when required, but no colouration or emphasis (try a 20Hz to 20kHz sweep tone to hear just how low they go - impressive!)
Soundstage: not huge, but nicely defined with good height and depth - with a good source, there are plenty of layers to explore
If you're looking for an uncoloured IEM for around $200 you'll be hard-pressed to find a better option. Other IEMs in the price bracket do some things better, but I don't think anything does everything as well across the board.