We've been on the Miracle and its sister ship, the Pride. Funny thing was, we didn't like the Miracle, but we did like the Pride.
They're nice ships, just don't like the way they laid out. But it's also funny how you can sail on the same ship and get completely different experiences. So while it may have been good one time, doesn't mean it'll be the same the next or vice versa. Crews are constantly changing, which will sometimes dramatically impact the experience. We once sailed on the same ship three times and the first two times we were not impressed, but the third time we had a wonderful experience - crew had changed, ship had been refurbished, and a new captain was in charge - completely different than the other two sailings.
Sorry, didn't mean to get off the subject. The Miracle is a nice ship and you'll enjoy your cruise, especially because it's to Alaska, which is an amazing destination.