By default, Mobile Express will prompt you to choose a printer every time. That's the best setting if you frequently alternate between printers at a given location, since that option brings you directly to a pick list. You can, if you wish, set Mobile Express to automatically print to the last printer used in each location. But if you need to change printers thereafter, it's a multistep process that involves navigating through four levels of dialog boxes.
The Mobile Express Driver provides a consistent set of basic printing functions that work across all printers. These include the ability to do two-sided printing, N-up printing (multiple images per page), landscape/portrait mode, a black-and-white/color switch, and watermarks.
If you need more in-depth features, however, Mobile Express is no substitute for the original equipment device driver. It lets you choose a different paper tray, but it can't tell you what paper type resides in each -- or if there is any paper in the tray at all. It doesn't provide low-toner alerts or support any other status alerts or advanced features (except, of course, for Xerox-brand printers).
For example, with a Canon black-and-white printer at Computerworld, Mobile Express let me change basic functions such as landscape and portrait printing and one- or two-sided printing. I could choose paper size, tray and pages per sheet, or choose a booklet layout in portrait or landscape mode with or without borders. But other features offered by the Canon driver, such as scaling, text/graphics settings and status alerts, weren't available with Mobile Express.
Xerox says that Mobile Express' discovery tool will find all USB- or network-attached printers, but it didn't always find the printers I was looking for. For example, Mobile Express did discover a nearby HP printer in my subnet, but did not find a nearby HP LaserJet 4000 printer that is attached to a JetDirect 300x print server within the same subnet -- at least not initially. Later, I did another discovery pass, and it briefly appeared before disappearing again.
I was finally able to find the LaserJet 4000 by using the IP search function and add it to My Printers; I could then print to it without any problems.
I tested Mobile Express with a variety of applications, including the Microsoft Office suite. Everything worked fine -- except for the old version of Portable Software's QuickExpense, which crashed when I tried to print using the Mobile Express Driver. Given the age of the application (circa 1995), I guess that's not surprising.