Well this confirms that Soundwave will be in the movie as I've read conflicting reports.

To be frank (sic) I'm not all that hugely excited about this news. I guess it's because of all of Welker's roles in G1, Soundwave was the one which was the most electronically modified. The bulk of what we hear as Soundwave's voice is actually electronic. Welker's pure Soundwave voice is actually just him growling - and sounds the same as Dr. Claw from the English dub of Inspector Gadget. You can hear in the episode "Roll For It" when Soundwave says, "Excellent Ravage" - Welker's voice is unmodified and it sounds like Dr. Claw!

This isn't to say that I'm not glad that Welker's in the movie and reprising his role as Soundwave... of course, we don't know how they're going to electronically modify his voice which, in the case of Soundwave, is vitally important in how he'll sound. To be "G1 accurate" Welker would just do his growling Dr Claw voice and then after that it's entirely up to the sound engineers. Still, the core performance that Welker brings is something I'll look forward to. It's something that other voice actors cannot seem to match IMO (e.g.: Animated Soundwave).