Although they require you to acknowledge the outage by submitting a support ticket while your server is down or it's not considered an outage (and that's not going to happen, specially for 9-minutes outages), they do say they offer 100% uptime.
How reliable is this? AWS went down many times, I doubt Vultr can actually do it, or I'm missing something?
They promise the 100% offer account credits if (read: when) they don't meet their promise. The cost of not meeting their promise, if caught, is minimal—if your $10/mo VPS is down for 59 minutes, they offer 24 hours worth of credit (which works out to about $0.33). Being able to make this claim is very much worth the amount they expect to pay out in account credits.
I guess everyone goes down. I'm building a GlusterFS cluster. I have 2 nodes with Digital Ocean, 2 with Vultr in Amsterdam, and 2 in Frankfurt. Hopefully the whole Vultr infrastructure won't go down for a long time or the 2 Digital Ocean servers will get a lot of load.