THE GOOD
 
Shure products are durable and well constructed. The cables are supple but very resilient. The IEM housing is durable as well as the MMXC connectors. Overall the construction is good.
 
Shure tips never come off and only with a struggle. You are  given a good variety of tips. 
 
They are good balanced IEMs where they excel mostly in good mids and decent lows and highs. 
 
I have sent in Shure IEMs three times and have them processed ASAP with care. No complaints here.
 
THE BAD
 
The bass feels a little enveloped or compressed. I am not sure what's happening but there's a noticeable drop off.

THE UGLY
 
I am not aware of anything really bad. Maybe paying full price?
 
OVERALL
 
These are my fallback IEMs and they deliver consistently good playback on most types of music.

This is my first review so keep that in mind.
 
I bought a pair used UE 900's at Cex, an electronics resale store in San Francisco. I was cleaning them and pulled the wrong way on the MMCX connector and the freakin' right unit came apart and ripped the internal wires apart. I contacted Logitech tech support and was shipped a complete UE 900s for a replacement! They were quick and helpful to respond, much better than I was.
 
So, this review is for the Logitech UE 900 and Logitech UE 900s units.
 
THE GOOD
 
These IEMs really excel at representing distinct highs. Cymbals, falsettos, and all high frequencies sound crisp and clear. Until I found the right ear tip, it was on the verge of headache inducing. These IEMs really require the time to find the right ear tip. 
 
There is low microphonics in these. They are almost silent with no music playing.
 
Bass is present but does not feel compressed or mangled. For me it's just enough.
 
Acoustic music sounds great with these. Vocals and guitar really shine through.
 
The sound stage feels medium-ish. The canal is wider than say Shure or Westone IEMs.  Not sure if that completely the reason, but like my Sennheiser IE80's it feels pretty full.
 
THE BAD
 
Mid frequencies are really not as noticeable and sometimes get lost. Female vocals, electronic music, etc. sometimes are not be optimal for these. They are not absent either. I wish it was just a little more.
 
THE UGLY
 
The construction is crap. For real. The cable and housing, while actually somewhat durable, feels fragile. I only sit and sometimes walk in these. Actually, the cheap construction helps in that people think you're listening to some crappy headphones not realizing that they retail for $300-$400. So you are less likely to get mugged in them :-D 
 
Also, they look a little "Fisher Price" like.
 
OVERALL
 
These are currently my second favorite IEM (out of my 5).  For the price the treble/bass combo is good, for my tastes.