Pros: Great mids. Highs aren't bright. Lots of bass. Price! Easy to amp. Sturdy (but a little cheap feeling) build quality.
Cons: Sometimes too much bass - it can get a little bloaty. In-your-face lack of depth in the soundstage. The comfies aren't that comfy.
Note: These were received as a gift.
In short, I'm actually stunned at the level of performance that only $110 will bring - perhaps it's just the newness to me, but the level of detail of the Alessandros sounds on par with the HD 600s (i.e. excellent), and the sound signature is (IME) closer to the HD 600 than anything else I've listened to, just a bit more "exciting" sounding.
What I'm most surprised about is that the Alessandros don't seem bright in the least - I was bracing myself for that, but it never came. Well, maybe just a tiny, tiny bit. There's certainly more of an emphasis on the upper mids and lower highs - and bass (leaving the low mids standing out slightly in the HD 600, relatively speaking) - but it's not fatiguing like I found the Beyer DT 880 to be.
The bass is surprisingly very strong - almost verging on being bloaty at times, but never to the point where it offends me. It's kind of like an exaggerated version of the HD 600 bass, perhaps not with as much extension. Note definition is very good, however.
The most notable difference (beyond the price) may be the soundstage, of course. The Alessandros are narrow, less precise, and closer sounding than the Sennheisers - I don't want to imagine how a K701 or HD 800 would A/B in comparison. It's not horrible when just listening to them, but as soon as I went back to the HD 600 for the first time, I was astounded at how much more enveloping they sounded. I guess some like the Grado presentation more (perhaps those who've never heard truly great speakers), but I can't say I'm one of them. Holographic these are not.
Oh, and the other downside: Comfort. The comfies are much better on my ears than the bowls - which are uncomfortable immediately upon putting on, and hurt after just a few minutes. Still, I'm finding that after an hour or so my ears hurt a little from even the comfies. I've stretched out the headband a little which has helped somewhat, although they weren't that tight to begin with and I kind of like not having the band touch my head at all. Anyway, all the popular over-ear open headphones I've tried, including my HD 600, are way more comfortable.
I love the looks, however, and the sturdy build is excellent. The cable isn't going to fall apart on you either; it's surprisingly very good. The plastic of the cups is a little cheap feeling, but it doesn't feel like it's going to break - same with the headband and the vinyl pleather.
They're very easy to drive - the Sansa Clip+ does great for a portable, as does the uDAC. Perhaps the uDAC has slightly more more depth and dynamics, but I can't say for sure. It may just be the difference in using the HeadPlug MKII crossfeed plugin on Winamp.
So there you have it - these are superb headphones - at any price - marred really by only two things: Unrealistic in-your-face soundstaging and on-ear uncomfortableness (for me). For the price, that's excellent.