Heh - the old vinyl vs CD debate.
In essence, it reduces to the physical properties.
Digital media can be more accurate, to the point that there is simply no way that vinyl can compete. 24-bit audio has a greater dynamic range and does not require compression (although over-compression is a sad fact not just in digital media, but also some vinyls - e.g. Metallica's "Death Magnetic" sounds awful on vinyl. That said, the CD isn't much better - but the versions that come with Guitar Hero kick ass).
Here goes for my attempt at an explanation - this is all based on stuff I've read in a wide variety of places, written by people who really know what they're talking about (unlike me - I'm just having a stab at interpreting it here!);
Digital audio is a series of bits - either on or off - and you would rightly suspect that stuff gets lost in this process, because audio waves are complex and curved. However magnetic tape relies on the orientation of iron filings, and vinyl relies on the positioning of relatively big, fat molecules - neither of which can possibly acquire the resolution or precision of digital bits.
This is compounded by the fact that vinyl is limited in dynamic range - I believe it has a ceiling somewhere around 16khz, while tape has a ceiling of 20Khz. This means that the very highest frequencies are lost when transferring from the Master tape. There is a low end limitation too - but I'm not sure where it lies.
I've also read that the human ear cannot detect frequencies above or below certain ranges - however, this varies from person to person. Recently, I went into a room at work where a monitor was whistling at a very high freqency indeed. I complained, and the other guys in the room looked at me in amazement, as they could hear nothing. I switched the monitor off and on again, and they noticed no difference.
The point here is that everyone hears stuff differently. It's to do with sound waves, vibrations and the vibrating atoms we're all made of.
In short - it's a preference, whatever anyone says, and I prefer the sound of vinyl.
However, it is true that a decent system will bring out the best from a piece of vinyl in a way that digital media can't compete with - because the source is analogue, it's more easily "coloured", so a vinyl can sound just OK on one system, but full of astonishing depth that you didn't even know was there on another.
...or maybe that's just me