When i bought this ¤ 150,= fretless bass, i hoped to get a decent spare instrument for guest players, and for the fretless experiment. When you buy a low priced (probably Chinese manufacture) product you don't expect to get great quality with perfect finish. However, that is what i got: the guitar not only is quite handsome to look at, it also is technically well designed (German or British design?) and manufactured and assembled with great eye for detail.
It plays unexpectedly comfortable and easy, stays in tune (also depending on your string quality of course), and pre-set parameters are perfect: string action and spacing, intonation, etc. It has an attractive sound to it, which could perhaps be a bit more specifically fretless. This might also have to do with the pickups, or the strings i have mounted (d'Addario ECB81-5 fatwounds).
Update 17.10.2017:
Now that i'm playing it through a BBE BMax Bass Preamp since a few months, the Jaco Pastorius sound is finally there, so even if the bass itself is not particularly fretless sounding, it doesn't prevent you from attaining that sound either, without use of specific effect devices. Just find the right preamp and the right settings for you, and this bass will give you a LOT of playing fun for an incredible price!!
Played the bass for many months now, very few drawbacks so far:
1.
Wear on the fretboard. This wood seems a bit soft (sensitive to wear by string friction), but it 'll be okay for some years of non-intensive use i suppose, when using flatwounds. These don't cause as much wear on the fretboard as roundwounds do. When going fretless on a cheap bass like this, flatwounds are the strings of choice. If i were Thomann, i'd sell this bass with flatwounds standard issue, because the rosewood fretboard was visibly damaged in the first month of playing roundwounds.
2.
In active mode, the battery drains even when the bass is disconnected. Whenever you forget to switch the volume knob to passive position, the battery will run out in about a day.
Pulling the volume knob (passive mode) prevents this battery drain, but i tend to forget this or accidentally push it into active mode. At any rate, when your battery is out, you can still play in passive mode.
3.
A bit annoying, even though the bass is so charmingly priced, is the fact you cannot adjust the intonation while your strings are mounted and in tune. The tiny bolts that keep the (individual) bridges in place can only be reached when you loosen or remove the string, meaning you have to adjust your intonation several times by the trial and error method, until it is exactly right. This of course only happens every time you switch to different strings, so once set you are relieved of this time consuming task for quite a while.
If you don't like to spend an hour on this task that normally just takes five minutes, you could mount a Shaller 3-D5 B replacement bridge available at Thomann.. that one looks very good and from what i can see precisely fits this guitar. Considering the upgrade...
Conclusion: have been playing it for almost a year now and still quite happy!
Addition 17.10.2017: DUNLOP Lemon oil seems to protect the fretboard pretty effectively. Since i treated the board about a year ago, the flats mounted thereafter have not caused any visible additional wear.