I think it comes down to how the montage is handled, and that Lorne and HappyDaze both have a point.
Yes, the ESB training sequence did reveal a few things about Luke's character as well as tease his connection to Vader, and that Luke still had some maturing to do (he got rather petulant about failing to move the X-Wing, showing he still had a lot of maturing to do), but there were some snippets that could have been trimmed. And apparently there were extra bits in the script that got trimmed anyway, such as one sequence showing Luke practice his Force-enhanced leaps, first with Yoda dangling Luke's lightsaber from a high tree branch, and another with Luke having improved his leaping ability to make a rather prodigious jump but fall a bit short of the mark, landing in a pool of swamp water and getting Yoda soaked in the process, which then cuts over to the handstand/levitation sequence.
I think an in-game training montage can be useful, but should be used sparingly. Of course, YMMV as to how sparing is sparing enough.