I was sparring a few days ago and i was up against someone who was good at fighting but when it got to the ground i had total control and beat him in a second. I think ground fighting is very good in sparring or maybe in real fights, because i been in some fights where i resorted to groundfighting.

whats your opinions on the subject of groundfighting?

Only go to the ground if you have to, otherwise it's completely pointless. Especially when your fighting on hard surfaces, or dirty surfaces that might have a used heroine needle or shards of glass or other bullsh!t on it. Plus if your opponent has friends around and they swarm you, you're f*cked. Fighting multiple opponents on the ground is utter BS, that thread is rediculous. Skill goes out the window when it comes to large mass attacks (4 people or more). You only have two eyes, two arms and two legs, and can't be everywhere at once. A good stomp on your head from one of the enemies will have that fight over. That's not to say it's impossible to defend yourself from mass attacks, standing it's VERY possible, and on the ground it is as well, but it is not easy!

Whilst I agree with the above post, it is important to add that the groundfighting phase is the area in which a skilled fighter is best able to neutralise and dominate a less able opponent.
Also, in an uncontrolled situation you might end up on the ground whether you want to or not. Good skills in this area are surely your best chance of getting back to your feet.