It is very good! But...

it is very expensive. There are apps of the same or higher quality with the lower price tag.
But OK. I wanted it because it sounds amazing so I paid for it. No regret there. But what bothers me more is the UI and MIDI crashes a lot. Such a cheap looking sliders. Generic! Some hyper lousy pictures on "Select Instruments" Horror looking. Like 35 mm negative. Do not get me wrong. Playing board is good. Strings are responsive and it is fun to play. But those sliders and buttons. Also very important miss. Is should have XY-pad for wah-wah and fuzz pedals. For us extreme bass players. For bends with bass and drums only.
Bass guitar world is not always the clean sounding one. As you can read the app is good it is recommended but it could have much better user interface. In artistic way. Not this ugly generic once.

Staklena Voda about iFretless Bass, v3.6.2.3