When I opened the box, I was surprised by how small, lightweight and compact the speakers were. I was convinced that the best I was going to get was an "ok" sound, if I was lucky, and hopefully not too painfully tinny, like most speakers this size. I was already thinking about if I'd have time to return the speakers when I plugged them into my satellite radio unit and turned them on - WOW! I was genuinely impressed. I didn't have to listen a minute to judge if they were ok sounding, it hits you right away. While certainly not high end audiophile quality, the S135i's give a very clear clean sound which is easily capable of filling a 10x20 room without distortion. These are excellent as a small portable speaker system for a laptop, MP3 player, TV, or satellite radio. Much better than most boom box setups twice the size.
Technical info - not much to this. There is an integrated iPod dock and although the specs say it is not compatible with iPhone, the iPhone certainly works - I tried mine. Technically, Logitech is honest when they say the S135i is not fully "compatible" with the iPhone. When I plugged mine in, I got a message that the attached device is not fully compatible and you might have cell phone interruptions - you then just cancel the message and play your songs while getting charged. (set the phone on airplane mode to block calls, if you like) For the iPhone, you just need to remove the plastic adapter plate used for the iPod. It just pops out. The auxilliary 3.5mm stereo plug in the back takes both line output from my satellite radio as well as earphone output from other MP3's. All very simple. I was wary of the Bass Boost since most are awful on these small systems but it actually works very well. Doesn't muddy the sound and is really more of a true equalizer setting. I like the sound just fine without the bass boost but if you like the added bass, it is a nice option. Haven't tried batteries, but other reviewers have indicated good battery life. These speakers would be great for outdoors with their big sound.
Overall, great value. Very good sound quality at a bargain price. You can easily spend a lot more on other speakers and get a lot less quality.