Pros: Sound clarity.
These were one of my first high-end earphone purchases, and it did not disappoint.
Before buying, there are a few things to consider regarding the Klipsch Image range. I was looking at the X5 and the X10, as both had good reviews. I ended up buying the X5 for the following reason:
1: it was cheaper
2: it was slightly heavier than the X10
3: the X10 is rumoured to be a bit biased on the high end, whereas the X5 is supposed to be neutral throughout.
The X5 comes in a handy carry box, with lots of accessoires, including an ear wax scoop (which was nice!). I would recommend the double-earbuds as they isolate a lot of noise.
As with most noise isolating earphones, make sure you get a good fit. On aircraft the plane itself can help you with this (changes in cabin pressure) and I have acheived some nice seals this way :)
The sound quality is awesome, and bordering good value for money. It is clear in the mids, the bass is not overly aggressive, and the highs are not punchy.