Well I know that very few people can answer this question, but you never know when Michael will come around here and share something with us.
Many people that watched the 20 min. screenings mentioned that the CG looks awesome, way better than the previous two movies.
Seeing the two TV spots really makes you think that this part will be even more demanding in terms of CG than ROTF (lets not forget that in ROTF there were 46 robots and Devastator which were a huge challenge). Also 70% of the movie is shot in 3D which also makes things more complicate. The time that they have for post production is 7 months and I really hope that everything is moving on schedule. This is very important for the crew spirit and especially Michael. Hope there won't be any compromises.
I hope that the fact that we still don't have a trailer and a poster is based on the new marketing campaign and not because of some post production delays. If the marketing campaign is new then I really hope they won't release so many TV spots as with ROTF. They showed us too much from the movie.
Also there are rumors that in May there will be many new info released about the movie. So as we love to say here May will be big.