Earning xper points will upgrade your level which will give you certain benefits like Xper Level 1 can post 2 questions and 1 take every 24 hours. Xper Level 2+ can send private messages Xper Level 2+ can post 5 questions and 2 takes every 24 hours. Xper Levels 2+ can add clickable links in their posts. Xper Levels 1-6 see ads. Xper Levels 7+ do not see ads. Guru/Master have their opinions on top.
So, earning xper would be a great idea for a better experience on the site. Good luck :)
My bro and I consider it to be quite irrelevant. All it does is give an indication of how long someones been here, and how many questions they've asked or answered. The only measure worthwhile is MHO, where people have tried to give the best possible advice or answer.