When you arrive at Pokémon X and Y's equivalent of Paris, Lumiose City, you'd do well to avoid the city streets. Not because there's some alien, Pokémon devouring creature hidden amongst the tall grass, but because that seems to be the site where a number of players are reporting a devastating glitch.
A number of players over at GameFaqs and a Tumblr page are reporting issues when saving their game while wandering the city streets. This action seemingly causes the player data to somehow corrupt, as upon trying to load the data, said players are reporting that the game promptly freezes, and the player can no longer progress.
As one player suffering from the issue reports, "...whenever I try to restart my game it immediately freezes. It loads my trainer and all of my clothes as well as the buildings and their lighting effects, but none of the objects in the streets or the textures on the buildings show up. Pokémon-Amie is also frozen on my bottom-screen without loading anything and the game won't return to the Home menu when I push my button. I can hard-shutoff, but the 3DS internal software is completely frozen."
Hard resets will at least get the player unfrozen, but subsequent re-loadings are met with the same freezing problem, rendering all progress in that file lost.
Thankfully, the issue seems to be fairly isolated, as not everyone is having (or at least reporting) the same problem in the Poké city of lights. However, don't go testing the waters, unless your want to risk starting your game all over again.
For players suffering from the glitch, there is something of a silver lining. Now that Nintendo's handheld DS line is WiFi capable, patch fixes are easy to both issue and install. Nintendo, however, has not issued any statement that it's aware of the problem, or has a patch currently in development.
Pokémon X and Y released recently, just this past weekend, and to rave reviews. Nintendo even held a special release party at its World Store in Manhattan to celebrate the game's launch.
The games represent a radical change for the franchise, the top down perspective having been replaced with more of a three quarter perspective, and battles look radically different. As per usual, players will see several new pokémon, 5 of which were teased in the game's trailer at the time of the announcement. There's the usual array of new starter Pokémon, and each game will play host its own type of new, legendary Pokémon. And what's more, a number of classic Pokémon have earned mega-evolutions they can transform into during battle.