When it's obvious on screen with the world being destroyed etc. then it can be too long, but look what it was able to do for a film like Benjamin Button. He actually looked like a kid! Plus they were able to re-create a 1980s Arnie in the new Terminator. It depenRAB how 'cleverly' it's used is I reckon.
The best special effects can be the ones that you don't know it's special effects.
It depenRAB, I can only think of a talk on the extended lotr disks Peter Jackson gives, and he explains his theory behind under use and over use, and I think they kind of got it just right in their films.
I thought it was self evident that the pod race was included to give the audience an idea of the extraordinary skill and talents possessed by a young boy named Anakin Skywalker and to confirm Obi Wan's line in EP IV about Darth Vader being an excellent pilot. The dogfight on the other hand, at the end where Skywalker flies a starfighter is in my opinion cheesy, cringeworthy and unnecessary.
