Personally I think the red is too deep, since it no longer looks luminous. It's sort of an opaque dark red now. I'd have been happier with a brilliant yellow or something, since they used to have a yellow lightning effect inside an orange-red glow. They were just too similar to the phasers before, so I understand the need for an update, but I don't think it looks good.
Less luminous is a good way to describe them. I tried equipping some AP beams since the patch (having used them way back) and something about them looked out of place.
I'd love it if they changed the color scheme to look like this, but it seems unlikely.
I think it would be completely sweet if they looked like the ghostbuster beams... just more focused and -straight-. That red and blue really accentuates the uniqueness of the beams from the rest of them out there and having that 'swirling' effect around the primary beam is really what makes it stand out as a truly POWERFUL energy type. Considering the bonus to crits... I think the appearance of Anti-proton beams are important to emphasize, and just a simple color change doesn't quite give it that extra visual punch that I would like to see.
It's honestly the entire reason I use plasma beam/cannon weapons. I don't particularly like the color so much (The bluish green is certainly not my fave color scheme...) as I like the large glowing 'starry' dual-heavy-cannon shots, and the spiffy 'fwoosh' sound effect. The beams are also appealing to me because it has a semi-jagged edge to it, giving the impression of a force so powerful it can't be contained in a simple focused beam. One of the aesthetic reasons I don't use phaser/disruptors if I can help it.
If Anti-Proton could just be more like the ghostbuster proton beams, I think it would certainly go a LONG way toward visualizing just how powerful they are in practice. Taking advantage of the bloom effect to give it a nice glowing flickering strobe-light-like effect would really help it 'pop' too.