I for one was certainly not blown away by the Westone 3. In fact, I kept them for a little less than a week before selling them because there were some aspects of its sound that I just couldn't stand. The W3 dethroned the Sennheiser HD25-1 for the headphones that I've kept for the shortest time.
I can see why some people like the W3, they are very musical and "fun" IEMs, but IMO they lack in some important aspects. First, to my ears, the vocals sounded veiled and far from what I'd consider natural. It sounds like the singer is placed behind the band and I had to turn the volume a lot more than my usual listening habits to hear satisfying vocals. In general, the mids were not detailed as much as I'd have liked and the upper bass slightly overpowered the lower mids, giving a U-shaped frequency response.
The second biggest flaw that I could hear was a very apparent roll-off of the high frequencies. That's exactly the reason why I sold the Shure E500 and the W3 didn't do much better to my ears despite having a dedicated driver for the treble. For reference, I tried all the tips and some opened up the treble a bit (transparent tips and grey silicon ones) while others made it a lot worse (triflanges and Complys). The good thing with attenuated treble is that it makes bad recordings sound better than they should, but on the other hand, good recordings doesn't sound as stellar because a lot of information is lost. Another effect of the roll-off is that percussions didn't have the snap and speed that I'm used to, they sounded mushy and imprecise.
Finally, something that bothered me a lot is that these headphones lack big time for the resolution of small details. They give a good general portrait of a song, but the little whispers and recording imperfections that I'm used to hear on other headphones were simply not there. It might be good for low bitrate files or badly produced records, but I expect more from 400$ headphones.
It's been mentionned that the tips change the sound quite a bit with these IEMs and I have to agree with that, but my general impressions remained similar no matter which tips I used.
The other IEMs I've tried before the Westone 3 are: UE Super.fi 5 Pro, Etymotic ER4P/S, APS recabled Etymotic ER4S, Shure E4, Shure E500 and AL im716. My reference headphones are Stax Omega II Mk1 and I've tried most of the best headphones (K1000, PS1, HP2, etc.) except for the HE90 and L3000.