I have been going since July 2008.
I actually have quite a steady work flow and have a guy working with me part time which works out brilliantly. In saying that though I am currently skint due to most of my recent work being commercial, which means it takes longer to get paid. It is one of those months too where I am shelling out for road tax, MOT, van repairs and insurance which I had budgetted for but there is always something to scupper your plans!
I think coming in with someone else will have its ups and downs as you need to be prepared to have little or no profit for around the first 2 years, so you are both jointly responsible for that and any liitle profit you do make will be halved and may not seem worth it. Having 2 people on bigger jobs is brilliant as you work far more efficiently and get more done within tight time frames.
A friend of mine came into it part time as he was still employed but he soon packed in his job and became a full time carpet cleaner.