If you're comparing these to the Ruggeds, in terms of fit there isn't a significant difference (that said, the Ruggeds don't have a flat cord). The inline remote is thinner on the S4i II, has a glossy finish, and smaller buttons, which makes it a tad more difficult to operate by feel. But that's not really a knock against it (in other words, it's fine).
As for additional accessories, the S4 II comes with a nice, compact carrying case. It's the same one that ships with the original S4 earphones and it's one of the better earphone cases out there because it's lightweight and compact, yet protective.
In the past, we've rated the S4s very highly for sound quality. Since Klipsch hasn't changed the sound profile, this model gets high marks, too, but it's worth discussing why a lot of people end up liking this line as much as they do. With earphones, one of the biggest keys to sound quality is the fit of the earphones, and the S4 II model fits exceptionally well. Again, that's partially due to the angle of the earpiece stem and the shape of the oval eartips, all of which allows you to get a very tight seal comfortably.
Listening to the S4 II, I can't say the sound is really that much better than you get from competing models. But the sound is nicely balanced, with good detail and ample though slightly restrained bass. They just sound pleasant and the bass response is helped by the tight seal and very good noise isolation (that said, if you are a bass lover, this isn't the earphone for you). In other words, there are other $100 earphone models out there that have the potential to sound as good as the Klipsch S4 and S4i II, but they don't necessarily reach their potential due to their fit. The Klipsch earphones do; you really get the most out of the performance they offer. (I also had no problem making calls with them on an iPhone).
Are there better earphones out there for the money? I'd say the less expensive
Of course, every ear is different, so some of you may not think these are supercomfortable or sound that much better than competing models. But I'd say there's a good chance the S4 II will fit you well -- and that's why I find it easy to recommend them to someone looking for sub-$100 earphones.
The original Klipsch S4 and S4i earphones have received high marks for their sound quality and comfort level. The one strike against them was that their cord was pretty thin and we heard complaints about them not holding up that well over time.
Like S4i Rugged, the S4 and S4i II endeavor to do better in that department and they now feature a flat, tangle-resistant cord. For someone who doesn't like the feeling of having an eartip jammed in your ear, Bose makes the $99.95
If you're trying to choose between this model and the Klipsch Rugged, I'd say they're both good choices, with a very comfortable fit, tight seal, and strong sound. While this model has a classier look and should work fine for lighter workouts and everyday use, if you really are planning to hit the gym a lot, the Ruggeds are the better choice because of their sweat-resistant design.