I didn't want to weigh in on this one with yet another opinion
but i'm bored at work this morning, so what the heck.
1. Good for you to get your youngster interested in deer hunting and in bow hunting, (even though its an xbow). that is fantastic, and i think once he hunts with the xbow for a few years and gets bigger and stronger, he'll want to make the transition to the vertical bow.
2. for those that say its easier to shoot accurately with a crossbow. yes, it probably is. Minners' mom is a classic example, first time shooting shot a good group at 40 yards. that is tough to argue with, so i won't do it. I see a lot of bow hunters at the range that can't shoot that good at 40 yards with their compounds. I will offer these though...
-When i bought my mathews back in 07 i was shooting in the backyard here in VA. I got the sights set, and my roommate comes out and wants to try it. now other than little kid bows he shot as a youngster, he's never shot a real bow before. so I explain to him how to use a peep sight, release, and which pin to use. at 20 yards, the first time shooting, this man is shooting 3-4" groups, and hitting the bullseye. his first time shooting.
-ex. 2. a few weeks ago i traveled down to Charlotte to visit some friends, one of which wants to get into archery, and he wanted me to bring my bow down. also, his first time shooting a bow. we go out in their backyard, i show him how to use the release, peep sight, pins, etc... and this man is also shooting 3" or so groups his first time shooting. we started at 10 yards and moved back to a touch over 20. he was shooting as accurate at 20 yards as most deer hunters within 5 minutes.
so today's compounds, with high letoff, releases, pins, levels, peeps, etc... arent' that difficult to shoot either. it just takes practice and familiarity with your equipment to become good. i'm certainly no olympic class archer, but i shoot a lot, and can shoot deer killing groups out to 80 yards. I watch guys fail to qualify to hunt on the army base i hunt on (a 9" circle at 20 and 30 yards 2 out of 3 shots), guys that have been bowhunting for years. i think its all a matter of just how much you want to practice and how much time you want to put in.
there are advantages and disadvantages to using xbows. they may be easier to get on deer with, less movement, etc... but they are also big, clunky, and the shots are louder. the game still has to be close. and i may be mistaken, but i often hear that the effective range of the xbow is less than that of a compound (not sure about that though). I use to be completely against xbows, but the more i learn about them, the more comfortable i am with people using them for archery season. personally, i won't get one until i'm too old or hurt to pull back my compound, but i can't really fault someone for wanting to get into archery, and if this is the opening step for it, then go ahead. I think once you get close to deer and feel that rush, it will be a natural progression to want to get the vertical bow next to add that much more challenge to the hunt. i could be wrong, its happened before.