The shield reflect glyph only works on shields on yourself, not cast on others, just as a minute detail most don't realize... In my honest opinion Disc does not have a choice in primary glyphs at the moment; Smite, Holy Fire, and Penance (With a small reservation about the Penance glyph, due to the mana cost. Easily outweighed by the huge on-the-move utility it brings).
As for Atonement, I'm currently progressing on Sha of Fear Heroic (7% last night, fuck that boss). And I can honestly say the only thing I do on that fight is DPS. Atonement heals do the majority of the work, and I only cast other spells at specific times, and of course Shield to keep Rapture on CD.
At the moment, especially in a 10man environment when you personally make a tenth of the raid (versus 1/25th in 25man), Disc DPS is far too powerful. Why is that, you ask? No, I can't do the same amount of DPS as real DPS. However, over the course of a good Sha of Fear Heroic attempt, I do nearly 40 million damage. Now ask yourself, next time you wipe on a boss at 1%, would you want the boss to have had 40 million less health or not? Yeah, I thought so.
Basically; Atonement is fine, but Disc DPS is too good. If you're not Atonement healing as much as you possibly can get away with, you're doing your raid a disservice.
Doesn't really matter in Normal modes I guess, but there's plenty situations in Heroic raiding where your personal DPS as a Disc priest can mean the difference between a kill and no kill - particularly during progress raiding when the last few % of a boss can be the most hectic.
So yes, Atonement is good. Maybe too good.