I liked the sound of the original IE2s and these have a very similar sound profile, with pleasantly full, though not incredibly deep bass and decent but not great detail. That bass is probably the best thing about these guys; while the detail is OK, I thought the treble was a touch harsh, compressing the range between softer and louder sounds. In other words, these earphones don't really bring out the subtleties in your music quite as well as we might have hoped. Of course, you can't ask the world of earphones in the $100-$150 range, but we've heard models in this price class that outperform the Bose.
If you're looking at the step-up "i" version that includes the inline remote/mic, I did make some calls while wearing the SIE2i and found the sound quality to be good and the people I called said I sounded loud and clear. You'll pay a $30 premium for the headset feature, but if you plan on using them with a phone, it's convenient to be able to make calls and talk without having to remove your headphones (on an iPhone, the music pauses when a call comes in and resumes when you hang up).
Like Bose's other "i" models, the SIE2i is made for Apple products and some of its microphone and remote features may not be compatible with Android and other smartphone models.
I review a lot of Bose products and while I tend to like most of them and really appreciate their ergonomics (when it comes to headphones, at least), I don't think I've ever called any of them a bargain.
Bose's standard IE2 and MIE2i models retail for $99.95 and $129.95, respectively. As noted, these new, more rugged models cost more. The SIE2 costs $119.95, while the SIE2i costs $149.95. Simply put, these shouldn't be that expensive (they should cost the same as the standard IE2 line, which should get a price reduction).
Now that we have that caveat out of the way, I can say that Bose has done a good job building an appealing sports earphone that's very comfortable to wear and fits securely in your ear. Many people don't like having eartips jammed into their ears, and these Bose are among the best of the looser-fitting, non-noise-isolating 'buds. They offer decent sound, with pleasant, plump bass, and they seem pretty durable (it's worth noting that while Bose products may be pricey, the company's usually very good about replacing headphones should something go wrong with them).
In terms of wired sports headphones, I think Monster's iSport Immersion earphones sound better (they cost around $99), but that's partially due to how they fit (read: jam) in your ear and seal out any noise. And yes, there are plenty of Bluetooth wireless headphones to choose from; most of them don't sound as good as wired models, but their appeal is in their cordless design. The Bose SEi2 and SEI2i, on the other hand, are strongest in the comfort department.
The good news is that Bose has a 30-day money-back guarantee, so you can try them out before deciding whether they're worth the money. For plenty of people, they will be. For others, not so much.