considering the size of these speakers, they put out good sound. the speakers i was using before these had to be plugged into an AC outlet, no option of batteries.
i use music for dance practices after school, and since i can't carry heavy equiptment with me, i just carry these and my ipod. i like that they punch out loud sound, unlike some other speakers i've seen. my friend has a portable speaker system that is the same size as mine, but hers isn't loud enough.
the speakers are about the same weight as my cell phone. i also love that it has the option of running on either batteries or passive mode (gets its power from the music player it's plugged into). i don't ever have to worry about finding an AC outlet.
these are a great choice for portable speakers!