A fully functioning port of the PC version
Nothing more, nothing less.
Therefore, the only changes lie in the game being "translated" onto the DS and its hardware. The stages have not been compromised with in any way, and all the features of the regular game are left.
However, the visual appeal of the game (which was what made me love it back when playing on a PC) have been justified, or altered, to fit the DS. Some of the colours and special effects have gotten "downgraded" either due to the hardware capacity of the DS _or_ its screen size.
This is most notable when you look at the special powers - they lack that sweet punch they usually have when you select them. A full-screen monitor gives more room for colours, animations and - I know that this is a puzzle game but hear me out - depth. This is kept, but not fully executed, on Two Wonders II.
Having said all of this, that is pretty much the only thing to remark on. The gameplay is intact, and the addictiveness too :)
Only question lies in if you can tolerate not having the full-blown graphics as seen/experienced on the PC... And perhaps if your fingers are up for the task of tapping your stylus for HOURS on end ^_____^
