I received mine today and I am so far fairly happy. I'm not sure if this is the right place for a review but I am going to compare it against the dragonfly red because I know at least some people were wondering about that.
The build quality on the dacport is full metal and inspires a little bit more long term durability confidence than the dragonfly red's glossy finish even though they are both metal. Certainly the dragonfly looks nicer but that isn't really a big deal to me. What I will say though is that the dragonfly red is a great deal smaller and less cumbersome so some highly mobile setups may benefit from that. The dacport uses regular micro usb which may be an advantage in some scenarios. They each only have one headphone out jack so there isn't much to discuss there.
As for the usage experience, the volume knob on this dacport slim is quite nice. It really does put its overall utility over the dragonfly because it has this functionality. I like hardware volume control a lot but that's just me. The Dacport does get a bit warm to the touch however, which does not really happen to the dragonfly, I'm guessing it has to do with a difference in the electronics layout as well as the lower power draw of the dragonfly. The warmth isn't too bad though, just leave it exposed to the air.
Sound quality wise they actually seem relatively similar both very clear without much noticeable noise. There are some subtle differences like slight differences in high end and low end color and tone that will come down to personal preference, with the dragonfly red playing it a little bit safer with the sound and the dacport being a little more audiophile oriented. There aren't any glaring audible differences in the sound but the dacport gets a great deal louder especially with that high gain mode. It's supposedly something like 270 mw (DFR) vs 450 mw (CDPT) output power. Though trust me when I say that the dragonfly red would surprise you with how loud its amp can push it. If you have high impedance headphones the dacport will be able to drive them while the dragonfly would struggle perhaps at times, however, the sound quality of the dac of either of these products wouldn't offer anything you should call the best sound quality you've ever heard or anything. So if you need serious juice and decent sound quality the dacport slim is great. I would stress that the dragonfly is more mobile phone friendly however if you were thinking about that aspect of it.
One more slight comment about the two of them. On most of my in ears which are at 20 ohms to about 50 ohms the overall resting noise is pretty much the same silent on both though the dacport does seem ever so slightly noisier. However, the sound quality is noticeably worse on the dacport when I use my 16 ohm headphones on it. Not only is the resting hiss a lot louder I don't think the sound is as clean on the dacport either. My guess is that this has something to do with the higher input impedance on the dacport.
They way I see it the dacport has these advantages: 1. price, 2. output power, 3. hardware volume knob.
The dragonfly red has these advantages: 1. very small size, 2. mobile friendly, 3. works well with lower impedance in ears.
I think the dacport comes out as the overall winner for audiophiles but I don't want to discount the dragonfly red's usefulness. The small size of the dragonfly red and the fact that it plays nice with my phone makes it a compelling option in its own right. At least to my ears with the 24 bit flac files I could find, I really couldn't discern between one or the other having "better" sound quality, they were just different. If you don't have high impedance headphones (>100 ohms), or even if you do, the dragonfly red can drive them, though perhaps not as loud as you would like. If only the dragonfly red wasn't so freaking expensive (sigh).