It's not the texture that's bad, it's the way it's used which makes it undesirable. That's a bright texture with pretty high saturation in color, so it'd probably be more suiting for smaller geometry and platforms, whereas a duller variant would be more suiting for the larger scales of walls. And there's basically no sector scenery throughout the level, which also probably comes hand-in-hand with the fact that your texture variation is sparse. You need to spend some time decorating the walls and fields with smaller cliffs and rock formations and stuff like that. If you can do all that, then I'm sure your level would look and feel fun to play as a result.