How can you say it is slow? It isn't out yet.
When it will come out it will basically be a high-end Android device that can be used as an Ubuntu desktop (all current HDMI adapters require power, so it won't drain the battery when you are using it as a desktop).
Perhaps this is a concern to you, but it won't be much harder to keep charged then it is to keep a current smartphone charged while using it. And if you really are concerned, buy an external charger / car adapter.
The Unity interface has been notoriously buggy and slow. Canonical write core parts of their OS in Python. All my experience with their software indicates it will be slow.
I don't think the people working there are incompetent, more likely overstretched to breaking point.
Unity on the phone (running on my nexus 4) is blazingly fast. I mean, stupidly fast. Android and iOS feel super laggy compared to it. Particularly Android.
It's fast and stable. Canonical write core parts of their OS in C. All my experience with their software indicates it will be fast.
Even some of their ubuntu one storage engineers know graphics programming well enough to win game programming competitions. They're good, and have copious free time to make this perfect.
