To me, ONLY buy DSTWO if you are interested in,
* Real time functions
* GBA/SNES emulation (if you have a DSi or DSi XL)
* Upcoming video player
If you are the type of person who just want to play DS games, I can't recommend DSTWO to you at this point. We are in the late DS cycle. While it is true it can play most games right of the spot, many major titles can be found patched online, so it can be play on all flashcarts. Before people start yelling at me, yes I do own a DSTWO. I have tried it and in the end it serves as my secondary flashcart. I primarily use Acekard 2i due to simplicity.