As ever the biggest benefit Sony's Walkman offers over the equivalent iPod is what should be a major consideration in a media player, its sound quality. It's a traditional Walkman strength and the E443 is testament to that, sounding far and away better than the current generation iPod nano, or touch for that matter. Even the YP-Q2, which sounds very good, can't compete.
Whether listening to MP3, AAC, WMA or linear PCM files you'll notice the E443 gives a warmer, fuller and generally just better sound than its near rivals. That said, I don't have a current iRiver model, which anecdotally could still best this Sony, but I'll warrant the difference would be small. Battery life is excellent, too. Sony claims 30 hours of music playback, but I'm sure I've surpassed that over the last few days.
The best thing about the great audio reproduction provided by the E443 is that it makes an investment in a decent set of earphones all the more worthwhile. Listen to a pair of Ultimate Ears 700s with an iPod touch and you might be forgiven for thinking Paramore's Brick by Boring Brick lacks presence low down, but from the E443 there's bass a-plenty, without it becoming overpowering.
You don't have to be borrowing a teenage girl's music to see the benefits, either. Something more grown up like Wagner's Ride of the Valkaries or Beethoven's Symphony no. 9 are an eminently listenable experience on the E443 to the extent that I'm not really looking forward to reverting to my iPhone for day-to-day music playback duties.
The E443's stellar performance makes it all the more galling that there's no support for any compressed lossless audio formats. Even the iPod nano will play back Apple Lossless audio, although I defy anyone to notice with its decidedly mediocre DAC. Sure, you could rip your music as WAV files, but carting around uncompressed audio rather negates one of the benefits of digital music. I'm pretty sure that while Clear Stereo purports to reduce leakage between left and right audio channels, it doesn't actually have a noticeable effect and the only other audio enhancements available are a bunch of pre-set and two editable equalizers, which hardly count - producers put a lot of effort into making sure an album sounds 'right' and I doubt you'll do a better job.
In case you hadn't noticed, my criticisms of Sony's NWZ-E443 are basically just nit picking because the fact of the matter is that it's a cracking good small media player. It might not have the out and out aesthetic appeal of an iPod and it may lack the snazziness of the YP-Q2's touch-sensitive controls, but if all you want is a focussed music player that sounds good, nay great, then the E443 (or one of its higher capacity siblings) should be your first port of call.