Overall; the sound quality and available loudness from these speakers is really quite remarkable, and added to their portability and optional battery power they are really a bargain.
I received these speakers as a gift, so didn't have a chance to read reviews or test them against other speakers, however I needn't have worried about their quality; I don't know if the older i-station 3 speakers with the extra sub-woofer are to be phased out, but they really don't sound any better than these speakers. A small sub-woofer isn't going to make a lot of difference anyway, and comparing the two designs I think these are just as good and a lot cheaper (I have heard both).
The overall size of the folded speaker set is about that of a small paperback book; there are clear plastic covers built in that fold over the speakers to protect them and the base unit which holds the ipod folds up into the body of the unit. Several adaptors are supplied to hold whichever ipod you own, but you will need the adaptor that came with your (original model) nano if you want to seat that securely.
The unit is very simple to use with only a couple of buttons for volume up and down and the on/off switch. The on/off switch is illuminated blue and is really bright. Because your ipod is connected via its USB socket the volume can only be controlled from the i-station buttons; these can be adjusted from silent to max volume quite quickly and easily with a couple of pushes (and I've edited this because I said they wouldn't go down to zero volume previously - I've since found out that my original unit was faulty; the new one is fine) You can also change the EQ setting on the ipod itself and this will change the sound tone from the speakers, although I found the setting for 'small speakers' was a bit bassy and muffled. The'rock' setting is good. Sound quality is really very good for such tiny speakers, and as I've said the available volume is excellent.
If you want to connect any other type of portable player a headphone adaptor lead is supplied that will allow the output of any device with a 3.5mm headphone socket to be amplified (which is anything and everything really - cassettes/mp3 players and portable CD players).
Talking of leads; a mains lead is also supplied and is colour matched to the main unit too. If you use this the player is slightly louder than with just batteries, but it is the battery feature that makes this player so good - battery life seems to quite amazingly good. I put in a set of rechargeable li-on batteries over a month ago and they are still going strong. I was really expecting the battery feature to be a bit of a gimic with them only lasting a few minutes, but the minimal battery consumption makes these speakers really great to carry around without worrying about extra leads/adaptors. You can actually charge your ipod when the mains adaptor is in use, but not when you are using just batteries, so you still have to note if the ipod is charged if you are out and about. I suppose it would be handy to be able to recharge rechargeable batteries within the unit, but you can't have everything I suppose!
A USB adaptor lead is also supplied that will connect to a computer and you can sync with itunes whilst listening to your ipod, even if you are using the speakers own batteries.
Overall I love these speakers and would recommend them highly to anyone looking for either highly portable speakers, or just great value.