Someone who is a physicist has this to say on IMDB about the movie:

http://www.imdb.com/title/tt1454468/board/nest/218339939?ref_=tt_bd_5

Certainly, things like this might happen in low Earth Orbit, with all the junk that is in orbit around Earth.
Most Satellites are in a much higher orbit than the Shuttle and the ISS usually go, as is most of the junk.
But there is allot of stuff up there, so it is quite possible that things in a higher orbit might collide sending meteorologic debris into a lower orbit unexpectedly, so I do not find the premise of the movie that far fetched.

What seems unrealistic from the Physicist's point of view is the relative speeds between the debris hitting the shuttle, and the tethered astronauts with the ISS. What is shown in the movie clips is much too slow. Anything in orbit (at a similar altitude) that might intersect in different orbits would have a different velocity magnitude on the order of tens-of thousands-of-miles-per hour at a low Earth orbit. So it would be difficult to see individual objets of debris whizzing by at hundreds-of-miles-per hour. Even more unbelievable would be tethered astronauts flying into the ISS given that they were once in a similar orbit with the Hubbell space telescope, and then knocked into an intersecting orbit with the ISS. From the astronauts' point of view, the ISS would change from a "Star-like" visible dot to impact in a matter of a few seconds. The possibility of "Trying to catch onto anything you can" would be like trying to grab onto on a train to jump on if it was going over 1000 MPH.

For the sake of entertainment, I am willing to employ my "Willing suspension of disbelief" for the humanistic story premise this movie suggests. When it comes to "Science Fiction", I do look for good story, especially if it explores the humanity of the characters involved.

In actuality, if anything like this did happened in low Earth Orbit, the outcome for all involved would not be the subject of drama, but the one of tragedy. Do not be comforted by the outcome of Apollo 13. That miracle-like outcome was directly due to the ingenuity and cool reactions of highly trained persons, in a very tightly controlled situation with a relatively small mishap (in comparison to this premise).

Considering this is a fictional Hollywood story, and giving the assumption that the it turns out good in the end, my guess is that this feature ends in a form similar to "The Abyss", where benevolent, overseeing aliens rescue good hearted explorers who seek the unknown for the betterment of their fellow man.

Regardless, I am looking forward to viewing this film.