I own a few other fretless and also built a couple of them myself. This SRD900F is nothing short of stunning. The flamed maple top (doesn't look like it is a veneer) and semi hollow body, matching headstock, the exotic wood fretboard, and overall build quality, are all worth mentioning. Sound-wise, 2 electric pickups and a piezo that can be blended in, gives tons of tone options. The tuners are butter smooth and stay in tune effortlessly, a nice upgrade from the lower tiered Ibanez basses. The nut is cut properly to the right height, such that the first few "frets" don't go out of tune when you fret them. I have noticed the lower-tiered Ibanez fretless basses uses a normal nut, intended for fretted basses. This sets the string height too high.
The one I got has a really stunning flamed top, if only Thomann allows attachment of photos...
Some not so good points: The strings are D'Addario Chromes, one of my favs. But I think they have been left on the bass with tension for too long, and have no life anymore. They can't be intonated properly, and I have to shell out another 40bucks to change to a fresh set. This seems to be a common issue, as I bought a Sire from Thomann, also with Chromes, and same intonation problem.
Also, the surface of the whole bass is open pore, and there are some bumps that can be felt catching on my hand, especially on the neck. This is not a major issue, and I think the neck portion will go away with more playing.
The abalone inlay on the fretboard is beautiful, but they are confusing. The side dots are located on the lines, while the inlays are in-between lines. So they sometimes throw me off when play. I have to learn to focus on the side dots when playing, or black out the inlays with a marker (not going to do that).
Conclusion: I believe this is the flagship fretless from Ibanez, and it is being sold at a very reasonable price. There are other brands in the market that are non-flagship, with much less features, and are sold at much higher prices. If you have the budget, go for it, its worth the money.