I recently got an ipod touch for Christmas, and since I had discovered a month earlier that the DOOM classic was made for the ipod touch I instantly bought it. (Along with Duke Nukem 3d.)
In my opinion DOOM for the ipod is a great sucess. Not only is it a great looking handheld version of the greatest fps game, but it has multiplayer and everything you'd expect from the pc version. Now for being made for a "console" with no buttons what so ever, the touch screen controls are easy and fun to use. (They are easier to use and learn than that of Duke Nukem 3d I might add.)
But the game has a few errors I noticed. In one map there is a HUGE hom effect where the developers failed to give a rather large sector a floor texture. This really pissed me off as it was a quite noticable error. And ocasionally going to the menu and selecting a different map to play can cause the music to play funny or skip like a broken record.
But all and all the classic DOOM port to the itouch was in my opinion a great sucess and worth the near $7.00's you pay for it. (I got it for $2.99 being it was Christmas though.)
To get this game head over to the app store on your ipod, or read up on it at id softwares website. www.idsoftware.com
Although I haven't watched the whole thing, it seems to be an accurate demonstraion of the ipod/iphone DOOM game.