I did notice the self-referencing, and that was awesome. I’d have to go back and watch it with a notepad and paper handy to get it all. Which is really cool.

That aside, the major differences I noticed were the different emphasis placed on technology. Technology was much more in the forefront of “The Departed” - Costello (Nicholson) is exporting microprocessors. Camera shots seem to linger longer over computer screens. The same computer shots are present in “Infernal Affairs”, but not as emphasized. Also, a major point is the use of morse code by the characters (via cell phones) - which is interesting as this is in a way stepping back to a more primitive/restricted form of communication. However, using morse code is in fact the elegant, clever solution, and served to highlight the apparent increased tech emphasis of “The Departed”.

I think Scorcese’s matching of actors was actually quite brilliant. I have to say I prefer Sam (eqv to Costello/Nicholson) and by far Lau (eqv to Collin/Damon). Nicholson could have toned down his insanity (a bit) and it would have been much better (and more like Eric Tsang who played Sam). Damon had a very different take on the character of Collin than Lau was portrayed in “Infernal Affairs”, so it’s hard to find one thing that he could have done differently. For me it was suspension of disbelief, trying to reconcile the wussy/indecisve Collin with the Collin who instantly shoots fellow mob-mole (Fitzy?).
Tony Leung Chiu Wai was awesome as Yan (eqv to Billy/DiCaprio), but I thought DiCaprio was awesome too.

But this raises the question - what does a brilliant recreation merit? It seems to me that most of the “heavy lifting” was already done. Granted, recreations of plays occur *all* the time - new interpretations, etc. A key difference, however, is that for many cases, there is no recorded version of the original play. This is obviously not the case with a movie - the original media is preserved, almost perfectly. And this isn’t an old movie - it came out in 2002! I would never make a blanket statement that recreations are never “original”, but I have to wonder.

Clearly we rate a Shakespeare play performance highly, but differently from that of an original play. I feel that I’m according less merit to “The Departed” than I would to Shakespeare performance, and I’m not sure why.

How about Ewan Macgregor?

I haven’t seen trainspotting, but I have seen Big Fish, Moulin Rouge, and Black Hawk Down.