I play upright bass, and electric bass. A couple of years ago, I bought one of these rubber stringed basses--it's an "Ashbory".
I like it's sound, but my bluegrass bandmates find it too un-traditional looking for their taste!
Mooh's evaluation is dead on; it has a good bass-y sound, but the short scale is a problem. You need very good technique to play in pitch. Being an upright (no frets) player has helped.

But you can overcome the stickiness of the strings, and slide as much as you want--if you use talcum powder (baby powder)on the fingertips of both hands. You don't need a lot, just a bit. A small can of powder will last you a lifetime.

Rich McCarthy