Pros
Unpakt is a true startup. It is working hard day in and day out to launch a brand new platform that no one knows about. You have the opportunity to make your mark, be heard and bring your best to the table.
I was one of the first employees, back when it was still coming out of Pivotal Labs, and then was at the University Place location... and then re-involved later as a consultant. Unpakt offers a lot of opportunities to those who have a vision and drive and want to be a part of something with the potential to be big--and know that it requires hard work to get there. If you want to be a part of a startup that encourages input from others (but also expects them to act on their ideas!), check out Unpakt. But make sure to bring your A game!
Cons
If you're looking for a shiny "startup world" with lots of free snacks, flex time and ping pong, this place is not for you. A lot of employees have come and gone expecting to be pampered and catered to as "startup employees" - if that is what you're looking for, seriously, not a good fit.