Been there, done that indeed - it is a port, but what a port!
There have been many changes that are positive, chief amongst which is the color blending which makes the dated graphics look nice, though some might find the blur a bit off putting, overall it works well.
Now this game is not the greatest game ever, but it is a nostalgic title for me (which might be why i gave it a higher score than others) but i really like it. In fairness it has flaws: the biggest one is that the interface (not appearance thereof, but the operation) is poor. Although it is configurable, and the multitouch capabilities are well used, you have to make a choice, either you can't turn and shoot, or strafe and shoot... this is because you only have two thumbs but three controls, so you need to make a choice of what you're more likely to need, and personally i find, i'd strafe and shoot while adjusting my aim on a PC. None of that on the iPod / iPhone.
This however is maybe not a fault of the game (remember that it was Doom that really started to get people to use the mouse for aiming, not Wolfenstein) but rather an issue of age. And although back in the day i didn't strafe, now it feels missing (i elected to be able to turn and shoot).
The other problem is that the difficulty is off. I selected just right, but really there is a trade off, higher difficulty means more enemies that take more to kill. While lower difficulty means less enemies and less hits for them. The problem is with Episode 2 the difficulty amps up and those zombies with the guns in their chest take more to kill than the standard soldier. But you start the game (each episode) with only a pistol. Dying means you got back to only a pistol. So as you progress death has some grave punishment's attached, so odds are you'll (at least initially) dial down the difficulty, but as you progress this may change.
Wolfenstein 3D is an old game. There is little story, or if you are aware of the story (i didn't notice any narration) it makes little difference because you are always inside a castle and even when you are able to see the outside. Everything is at right angles, and everything is of the same height. The environment's appearance get's boring quickly, but this isn't a game that anyone would pickup without ever having seen the original on a 386. So i expect you to also have a nostalgic reaction to this title.
If you are in the boat of never having seen the original, this might not be the game for you, though it is the full title and it has been enhanced, it is still built on old technology and with Doom being ported at the moment, odds are that that will be the game you will want.
When i bought it, it was on sale, so it was cheap. Even at full price i thought it worthwhile, but today with everything tending towards HD, this is a title that proudly sticks to SD .... maybe even LD. But really that is what i wanted and i can't help but get enjoyment out of this title.
Finally, two features i especially like: The map, i don't recall the original having this feature and i do know that it is better than what Doom ended up offering with it's vector graphics. You can zoom and move about, and it is very helpful. Further the casual gamer feature: you play your game and when you're done you exit. Next time you want to play start the game and hit resume and there you are. Downside to this is though, that you can't really share it with someone else, and you can't really save progress, though you can jump to levels you want to play (but it's Wolfenstein ... i don't feel one level is more impressive than the next). Oh yes, one other notable change, doors and secrets open now when you approach them, which makes finding secrets easier (though it doesn't ruin it) and improves the controls (given the above mentioned trade-off ... it helps :) ).
So, for a trip down memory lane, now that you're older and not using cheats, this is a game that's very worthwhile to finally play for real. If you don't remember it though, it might be too old. I won't say it's too hardcore or too vintage, but it does help if you have the nostalgia factor, if not, knock two points of the score.