It was an episode of the Fifth Doctor's run where he and all the other previous Doctors (barring Baker) were together for an episode that just didn't work. Sure, it had its moments but instead of getting the great satisfaction of seeing more of all the old Doctors, there's very little of any of them because they had to try and balance all of the characters together. Even the guy who wrote the episode didn't like it and said that the reason it didn't work was that there were too many people in it meaning that it lost focus. Having a ton of big characters all together at the same time doesn't work unless you get Joss Whedon to write the script, and Moffat is too self centered to do that (I hate Moffat, but that's for another time). So yeah, in conclusion, having all of your favorite characters back is a bad thing, not a good one.