Dubois and Sons Pocket Watch c.1850+/- 18K Gold, Working Order

I recently inherited my Great, Great, Great, Grand Fathers pocket watch. He was a physician and immigrated to Canada in 1816, being born in Scotland in 1808 and died in Canada in 1884. He earned his MD at Edinburgh University so he may have purchased when their going to University between 1828-1832. On the inside cover it says "Dubois and Sons". It appears to have inscribed by a jeweller, the dates 05-04-66 and 16-05-67. These are probably dates when he had it serviced in the 1800's. So it appears to be at least 155+ years old.

Any information or thoughts about this watch would be helpful. It is in working order but I know much about it...is it of quality, a collectors item, is it of value, etc.,???