i think its worth it because of how accessible the game is. the moment you pick it and everything that you want to do in a pokemon game happens so quickly. you can breed soon you get a second stater right off the bat. and there are so many new features to the game that just make it fun. its been criticized as being too easy or not enough story but the games are centerd around raising pokemon and this game makes that easier and more fun than any of its predecessors. if youre a fan of raising pokemon this is for sure worth it. if you, for some odd reason, are looking to play through a long story and lengthy after game exclusively and are not so interested in the 450+ pokemon available to you then maybe you shouldnt. there are also so many big 3ds releases on the horizon such as super smash bros that youre going to ask your self this question again sooner or later and in my opinion you should buy it now because of this awesome game and future releases to come.
If you bought a DS for Diamond/Pearl/HG/SS/BW, then it only makes sense you should get a 3DS for XY, and all future 3ds pokemon games. Though its up to you and your econimic situation, and the investment you feel would be worth. Pokemon is awesome, ovbiously, and you'll hear plenty of praise here, and millions have bought a 3ds just for x/y. I would recommend it, plus there's lot of awesome games for 3ds, (luigi's mansion, mario kart, monster hunter to name a few)
I bought a 3DS before XY were announced but I only own Pokemon games for it. So I actually bought a 3DS for Black 2 even though it wasn't required. I prefer Pokemon Y over X due to the exclusives. I feel like X got shafted on exclusives. Anything worthwhile is breedable on my Y and their exclusive Megas are far worse imo.
Having the same internal battle myself! I work in a games shop in Aus, so I'm constantly talking to customers and staff about it and really want to play, but with the XBone coming out in a month, can't justify $200 to play one game!