This is a great workhorse printer from H.P. its fast with clear, crisp print results, the extra paper tray is useful for having plain and letter headed paper ready to print, or even different sizes.
Easily networkable, and the duplex is fast without paper jams which seems to happen often on other machines I've used.
This machine has a small footprint so if space is at a premium in your office but the workload is high, this might be the printer for you. Hewlett Packard make good reliable printers in general and if the LJ4250dtn develops any faults H.P. parts are cheaper and more easily available than most.
There is one fault I am aware of with this machine relating to the duplex unit, if you expect to do a lot of double sided printing, it has a habit of becoming a bit noisy; there is a cog that wears under the extra load caused by the duplex. However this is very minor and can be fixed easily.
With Duplexing, Extra tray, and Network card, this printer has all the extra's.... Shame its not colour too.
Having said that I really rate this printer, and would recommend to all.