Yea, if you want to jump in Right Away, go ahead and watch the Christmas Special, new Companion so, some of the most basic concepts of the Series are likely to be reintroduced in some way. Then go back to either Rose or The 11th Hour and watch forward.
Or just start at Rose (or The 11th Hour) and move forward from there.
Unless you've already become familiar with Classic Who, it's probably best not to start there, as Wormhole mentions the Missing Hartnell and Troughton stories can be an issue with you getting your bearings, and then of course there is the aversion some have towards Black and White TV putting a damper on the First two Doctors as well as a bit of The Third, plus the different story pacing in the old Series and the budget was pretty small so many folks laugh or groan at a lot of the effects. Classic Who, for new viewers of today is more to the taste of folks wanting MORE when they've consumed all of NuWho