The Canon EF 28mm f/1.8 USM Lens is currently Canon's fastest 28mm lens.
My first thought upon removing the Canon EF 28mm f/1.8 USM Lens from the box was that it was very similar to the
Canon EF 20mm f/2.8 USM Lens
in size, build quality and appearance.
And that is a good thing.
USM (Ultrasonic Motor) makes focusing much quieter in the Canon EF 28mm f/1.8 USM Lens
than in the Canon EF 28mm f/2.8 Lens.
This is also a good thing.
FTM (Full Time Manual) Focusing is a nice feature in this lens.
Focusing speed is similar to or a little faster than the f/2.8 version.
Also good is the Canon EF 28mm f/1.8 USM Lens's short close focusing distance.

Pictured above from left to right are the
Canon EF 24mm f/2.8 Lens,
Canon EF 28mm f/2.8 Lens,
Canon EF 28mm f/1.8 USM Lens and the
Canon 24-70mm f/2.8 L USM Lens.
One of my biggest disappointments in the Canon EF 28mm f/1.8 USM Lens is the very obvious CA (Chromatic Aberration) it exhibits at wide apertures.
Proneness to flare is another notable negative characteristic.
Otherwise, image distortion is low and colors are good.
The Canon EF 28mm f/1.8 USM Lens' bokeh quality is decent.
Out-of-focus highlights have 7 sides when the lens is stopped down thanks to a 7-blade aperture.
The Canon EF 28mm f/1.8 USM Lens exhibits softness wide open.
I generally find that when stopped down to f/2.8 or f/4, the Canon EF 28mm f/1.8 USM Lens is quite sharp.
The corners are best after f/5.6.
The Canon EF 24mm f/1.4 L USM Lens
and Canon EF 35mm f/1.4 L USM Lens
both are noticeably sharper.
The Canon EF 24-70mm f/2.8 L USM Lens
is noticeably sharper with the extreme full frame corners being an exception.
The Canon EF 28mm f/2.8 Lens is much softer than the f/1.8 - especially in the corners.

Pictured above from left to right with lens hoods in place are the
Canon EF 28mm f/1.8 USM Lens,
Sigma 30mm f/1.4 EX DC HSM Lens and
Canon EF 35mm f/1.4 L USM Lens.
If the Canon EF 28mm f/1.8 USM Lens' image quality is good enough for you at f/1.8, this lens will make a good low-light handholdable lens.
On a 1.6x FOVCF body, the Canon EF 28mm f/1.8 USM Lens makes a near-normal 45mm lens.
For those who have grown used to a 50mm lens on their film SLRs, you will feel at-home with a 28mm prime.
Canon EF 28mm f/1.8 USM Lens Sample Pictures ...
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Canon EF 28mm f/1.8 USM Lens at Adorama (Imported)
Canon EF 28mm f/1.8 USM Lens at Adorama
Canon EF 28mm f/1.8 USM Lens at 17th Street Photo
Canon EF 28mm f/1.8 USM Lens at J&R
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