Quite an experience though.
But it helped me quite a bit with the typing and I guess that's all I needed.
The connection was good, no stuttering etc with medium details. The problem was not with VNC but with android's heavy dependence on touch usage. I could use the keyboard quite proficiently but many touch gestures needed for navigation meant I had to reach to phone for app switch, notification access etc.
Next I tried a number of VNC servers. The problems is most VNC software in play store is VNC Clients. But finally I found Alpha VNC and this is a good vnc server. I started the program. It has a nice round button with Start as text. Tapping this started the VNC server and it showed the connection details. I have the mobile connected to my desktop via USB Tethering so they are on same network. Next I fired up Remmina on ubuntu and entered the VNC connection details(IP and port) and connected.
I tried to use USB Debugging first thinking it would give better (ala faster) experience. I even found couple of apps on play store. But was soon bogged down in details of supporting apps, rooting etc. So I discarded this approach for another day.
Recently I wanted some task performed for an app which meant I had to type in quite a bit of data on my phone. Now using a real keyboard is always preferable. So I tried to share the screen of my android phone with my PC and tried performing some typing.There are two ways for this: 1. USB Debugging connection 2. VNC