I have tried Unicorn basses and they are great. In this case "great" means that they are head and shoulders above any other bass I have tried, and please note that I am not exaggerating. I had been looking for a nice fretless, preferrably a five string one, with a big, rich, "luxurious" sound. Not the nasal "Jaco burp" but more like something you would hear from Yellowjackets, Rippingtons or some smooth jazz band. After some underwelming experiences with the 2008+ MIA Fender Jazz, Warwick, Yamaha etc, I found out about luthier Christian Olsson and Unicorn basses.
Funnily, it turned out he lives only a few kilometers away from my parents! I talked to him on the phone and he invited me to the workshop.
His work shop is smallish (as he is doing just a handful of basses in each batch and much of the work alone or with just one employee) but equipped with a set of modern machinery to do top notch wood work and great finishes. The instruments are very high precision built (far beyond something you normally see in a MI shop) and with a timeless design, if you ask me.
Christian is very forthcoming and good at interpretating the customer's sound ideal and ergonomics into a "blueprint" rather than just talk about the specific technical details. (I guess it would be very easy for most bass players to get lost if one were to pick the best kind of wood, neck design etc if nobody told you the total outcome of your selections?)
On the other hand, I am sure he could also discuss and evaluate every single layer of laminate in the neck, should that feel important to the customer...
I tried a fretless, four string Neo bass, one of his demo basses and was very impressed.
Even for me who was rather new to fretless it was clear that this was a gem. That bass sings in every position on the neck, "mwah" by the truckload, with very even and clear tone across the neck and with looong sustain. (Typical for his products, it seems.) Tone was clear all the way to the fundamentals, very refined with polite midrange and it responded so well, even to my fumbling fingers...

It was "record ready" without any Avalons or Demeter to sweeten up the tone. Even the typical four string, dreaded dead spot problem was virtually non-existant on this bass, too.
The only frets (sorry) were that that bass was active (I wanted a passive bass) and that I personally preferred the Ozellman body shape.
After the visit I tried another few basses in the same price range but nothing sunded as good or felt as good to play as the Unicorn.
So I ordered a fretless five string Ozellman Basic, which it still not completed. (Having waited very long now, it better be good when I pick it up...

)
A while ago I tried its "brother" a fretted five string Ozellman basic and it felt very good, so I guess mine is worth waiting for.
And just for comparison; byt the time I ordered my bass, it costed only marginally more than a fretted MIA Jazz V. (Fender has since dropped prices in Sweden noticably.)
/Alexander
PS.
I am not in any way affiliated with Christian Olsson or Unicorn bass.