I bought these speakers as my logitech ones died and I wanted an upgrade. These do not disappoint.
Firstly it's important to put these speakers in context, for PC speakers these are expensive but in terms of hi-end audio products...Read more these are dirt cheap.
As PC speakers these are blindingly good, not only is the sound much much clearer and richer than regular PC speakers the staging capabilities are great too. By that I mean the music has spatial position, for example when a centred sound is played it sounds as if it comes from my monitor not the 2 speakers. While many speakers will be able to produce the same amounts of bass and treble they just don't provide the same sonic experience as these do. The lack of a sub in my opinion is a good thing, it means the bass isn't coming from the floor ,and as such gives a truer sound. There is an extension available but these have plenty of bass to satisfy everyone but a hardcore German-techno fan.
Depending on what you use your speakers for, and your own ears you may want to add some eq, I have a very very gentle slope at the bass end of the eq on my sound card, this isn't really necessary but I find this helps eliminate the slight boominess that these speakers can produce under certain conditions.
On certain recordings the sound might not be absolutely perfect, either a tad too sharp or too boomy, but I really mean a tad, and a bit of EQ adjustment can usually sort it out, usually it is a problem with the record itself though, not the speakers themselves. I am being extremely picky here so don't let this put you off.
If you have an X-fi card it makes a good pairing. I recommend that you turn the crystalizer function off when listening to music, but on when gaming (i.e off in entertainment mode and on in game mode). It's quite a good function on cheap speakers because it helps bring out attack but these speakers don't need the adjustment and turning it on leads too unnaturally snappy sounding music, the only time you might want to turn it on for music is perhaps an older, less refined recording. The same applies to the CMSS settings, turning it on will ruin the stereo soundstaging in music but for games and films it works surprisingly well by creating virtual surround sound.
There are competitors, the m-audio av-40 and samson studiodock 3i to name a couple, I have no idea how they compare sonically, I've heard that the AV-40s are fantastic however for a desktop setting they look a tad big so you won't find anything else for this size and price and styling. If you have a massive desk or are using them for something else it might be worth giving the other models a look however.
Lastly get the rubber stands, it's incredible how much of a difference they make, they should really include them with the speakers.
Summary - a fantastic package miles ahead of regular PC speakers, bringing high quality audio to your desktop.