I spent a long time looking at iPod/iPhone4 docks that offered good sound quality for reasonable cost. There are of course the brilliant B&W speakers (Zeppelin and Mini) but they are over my budget. My criteria was a) good sound, b) supports iPhone4, c) reasonable cost.
I found most docks on the market had a good price point (sub £100) but the sound quality wasn't good or didn't fully support the iPhone4. The S715i although was more than I wanted to spend, is worth every penny considering the excellent sound quality. It manages to be superb sounding speakers and fully supports the iPhone4 in a compact portable package.
The speakers are well designed and reassuringly heavy for its size. The build quality is top notch and feels like a premium product. There are only a few buttons on the main unit for volume control and power. The included small remote has basic controls such as volume up/down, track forward/back, pause/play and power on/off.
The sound from these speakers is quite amazing. Nice deep bass, with good mid and high end range. I have tested the speakers with a wide range of music and did not experience any distortion of any kind at high volumes. The sound was clear and dynamic.
The iPhone4 works flawlessly with these speakers. No issues at all regarding general operation. One thing to bare in mind though is that if you have an iPhone4 protective bumper or case then this might get in the way of the dock connector. This means that the case will have to be removed every time you wish to dock the iPhone4. This is the only negative point. But to be fair that is not the fault of the speaker design.
Overall I am very pleased with these speakers and is highly recommended for iPod/iPhone users.