EF 24mm f/2.8 IS user opinions?

Hello, I'm contemplating this lens.  In the "wide" category I currently own:

40mm f/2.8

28mm f/1.8

20-35mm f/3.5-4.5

I am extremely happy with the first - seems to me that Canon is knocking the ball out of the park routinely with their new lenses in terms of IQ (pricing, well that's another issue).  This is one reason I'm intrigued by the new 24mm lens.

The bigger reason is that I'm only moderately happy with the 28/1.8 and 20-35 - mostly for IQ reasons (the biggest reason, of course).  Under ideal conditions the second two do quite fine actually - it's just that they both seem to fall apart with any amount of backlighting which limits their utility, and makes me question my composition more than I'd like to.  I also do not like the size of my current lens collection, and am looking for ways to pare - replacing these two with a single, similarly small lens is appealing.

However, I'm worried I'll miss f/1.8.  The 28/1.8 isn't all that great below f/2.8, but it does produce an image below f/2.8 which the new 24mm obviously cannot.  I've got a 50/1.4 so that would satisfy any shallow DOF needs I have.  I'm less worried that I'd miss 20mm, but that's also a thing.

So, I'm looking for user opinions of the new EF 24mm f/2.8 IS.  How is the IQ?  How is the flare resistance?  Satisfied with backlight handling?  Any other comments are quite welcome.