Some people from the Gurren Lagann team were guests at the convention Connichi in Germany and showed the movie there in the evening on September the 12th for free. Unfortunately, there were no subtitles, but most parts of the movie are straight from the TV series, so it was understandable even with only minor Japanese skills, if you watched the TV series so far. However I also think that the end is new and great, but the new beginning is also shown in the last Parallel Works video (if I remember correctly). When the character designer was asked one day later, where he sees the differences, he told the audience that the breasts of Yoko are bigger in the movie....
But I must say that the movie is probably a little bit rushed for people who haven't watched the TV series.