I think the character overload wouldn't be so bad if it was the same characters past and present, but that doesn't seem to be the case. It looks like only Xavier, Magneto, and Wolverine are around at both time points.
First Class was very good, but now that they have decided to continue on after the original trilogy, that brings X3 back into the picture. But hey, in a JJ Abrams' Star Trek type way, this one looks to be completely destroying that time line, so I'm cool with that.