You picked a very good machine. I do see people occasionally selling used ones, but I've never seen a person accuse XP of making a crap detector. The Deus is a bit unusual in some respects and some folks have a hard time getting used to it. I can completely understand this.
It does not excel in every area, but it's pretty damned good (definitely good enough anyway) in almost every area, and the overall package is just a pleasure to use. The menu is quick and intuitive, the machine weighs next to nothing, no wires...you know the drill. The ergonomics are just nice. Mine was supposed to be my rainy day machine, but it quickly became my sunny day machine as well simply because it's so nice to use compared with my other detectors. My Minelab generally stays in the trunk because I can't be bothered to swing it, and while my uMax is nearly as pleasant to use, it simply can't match this level of performance. (To be fair to the poor uMax, it's an entry level machine and this isn't a fair comparison, and it still rules the roost in terms of finds due to the virgin sites that I was able to hit with it.)
A useful bit of advice that was given to me, and that I only partially followed, was to use a factory preset for a while in order to learn the machine. I started with one and quickly began changing things based on theory, rather than observation. After the observation period, I changed them some more...and now I'm pretty close to being back to factory settings.

(My standard park program is damned near Basic 2 with a pair of notches and one or two other small tweaks.) There are guys on the UK forums with experience going back years, right to the beginning, who are still using factory programs and doing well. The Deus has a lot of settings that can be altered, and some of these settings affect other settings in ways which aren't immediately obvious or even particularly well documented. To go along with this, I'd also suggest to stay with the same preset once you've settled on one. People often speak of detectors having "languages," and the key to successful hunting is becoming fluent in those languages. Note that a given Deus is Deus Fast is not speaking the same "language" as a Deus in Basic 2, so frequent changes will likely result in some confusion. Changing the settings (particularly settings like frequency, reactivity, silencer, tones, etc.) will change the "language," so make these changes sparingly and only after you're understanding what it's telling you.