Blu-ray.com has the details:
1080p high definition and framed in the movie's original 1.85:1 aspect ratio. For what the movie is, it looks great. ... Fine details...look rather good ... surprisingly solid black levels ... you are seeing is exactly what the filmmakers intended for you to see, and this disc definitely provides viewers with the raw feel and gritty look that is the true star of the movie.One important thing to note: ALL of the video in Cloverfield was shot in HD, even the scenes using "handheld" cameras.
Cloverfield devastates Blu-ray with a Dolby TrueHD 5.1 lossless track ... this one could be considered the best on the market, a sound mix many other movies of this sort could and should aspire to, and is certainly exemplary demonstration material ... The entire soundtrack is awe-inspiring, remarkable stuff. Kudos to Paramount -- what a fantastic way to truly kick off their return to Blu-ray.The Blu-ray exclusive feature is the "Special Investigation Mode":
Next up is Special Investigation Mode. This is a clever and entertaining way to watch the movie. The movie plays in a box while the remainder of the screen provides a map showing the current location of the "large scale aggressor," "human subjects," and the "primary military activity." Facts about the characters, the monsters, and various locations around the city also appear at regular intervals in another box.This sounds very similar to the UGO interactive map.
After reading a handful of reviews, I haven't been able to find any screenshots of the Special Investigation mode, or any mention of Easter eggs. If you see anything, let me know! FWIW, Walmart.com lists the same Easter Eggs as the standard DVD.