Finally watched Alcatraz last night on DVR. I liked it. It has the potential to get tedious - they catch one dangerous escapee every week, blah, blah. But I'm willing to give it a few more weeks.
As to being realistic - whether or not anybody successfully escaped from Alcatraz in real life is not pertinent. In the show, it's clear that the "escapees" and missing guards disappeared, and have come back 48 years later without aging at all. So it's obvious there is some supernatural explanation for this, that they will slowly reveal clues about, and finally explain in the last show of the series. This is the same plot device the producer (JJ Abrams) used in Lost. Many viewers suspected that the people on the island were all dead as a result of the plane crash, but it wasn't revealed until the series finale.