I've had one about six months. At first there were some teething problems which were resolved by, errr, reading the manual
Use of the Jobo has improved my C41 processing a lot, by maintaining the required temperature and standardising the agitation pattern. Same would be true for E6, but I'm not doing my own E6 processing at the moment. Economically, you have to have a reasonable throughput of films needing processing so that you use up the chemicals before they are expired; and splitting between C41 and E6 reduces the useage of the each set of chemicals.
If you're only doing black and white, a Jobo is probably overkill, although if you get one to do colour, you might use it for B&W as well.
The only downside is that I personally find the Jobo reels a lot harder to load than the AP reels which I have for use in a Patterson tank. The AP reels have a broad platform at the point that the film enters the spiral which makes things a lot easier. Oh, and this is a minority interest, bu my Jobo reels don't have a spacing option for 127 film so I'm still using the AP/Patterson combo for 127; even then the Jobo kit can be used to get the temperature of the chemicals right.