Pros: Very good detail and excellent recreation of the recording environment
Cons: Extreme top end lacks a tad of sparkle, but fine for most listening.
I`ve had these for about 2 months now so I think I have a pretty good idea of what they are all about. Before I started using them, I let them burn in for about 100 hours. Previously, I owned a pair of Sennheiser Momentum IEMs and a pair of Shure 215s. These are far better than either of those two. These really make my commute more bearable.
These are more detailed than the Sennheiser Momentums and have more bass then the Momentums or the Shures. But what I like about them the most is how they recreate the recording space and how they reproduce the human voice and instruments such as the piano or violin. On these things, the 750s really shine.
I compared them to the 850s briefly in the store and the 850s sound like they are a bit hotter in the high frequencies. For some, this is preferable; for others, this is artificial. Also, the 850s, because the in the interconnects built into each cable, feel heavier. I think the 750s sound a bit more natural in the high frequencies, but reasonable minds will differ on this.
All in all, I am very satisfied with these.