I was listen to Desert Urbania by uneXpect some hours ago and came up with this. Also first time writing for a six stringed bass!
It's pretty good so far. The 6/4 riff was well executed and flowed well. My only suggestion is that you take the octaves off the bass part during the 5/4 riff. It's not like they sounded bad, but it's not really possible to play effectively. The E string just gets in the way. Keep it up though. Good work.