They've changed Starscream's voice
Chris Latta, the actor who did Starscream's voice all those episodes, died a long time ago in 1994. Also, Megatron is done by another actor as well, Frank Weller who did the original Megatron wasn't used...
Megatron isn't a gun, not sure what the hell he is, but he's still cool.
Some kind of plane I believe.
Bumblebee isn't a Beetle anymore, but his character is still the same.
VW didn't allow them to use a beetle for Bumblebee.. Hence the scene where he hits a VW.
Biggest things I missed or didn't like.
To little time for Megatron. No bickering (sp?) / powerstrugle between Starscream and Megatron.
No Soundwave (not in the way he was in the anim).
The ability to chance into something different. In the original they were "stuck" between robot or 1 disguise. Here we see Bumblebee change from old model into a new model and "Soundwave" turns from a radio in a mobile phone.
All in all, good introduction to Transformers for those who didn't watch the original show, a reasonable film for those who do. They say a part 2 and 3 are comming. I hope they do more with Starscream vs Megatron.. Personally I would have liked to see them redo "More Than Meets the Eye" (the first 2 episodes)
(I guess I should say... BUMP... :-P )