f/5.6 --> f/6.3 is 1/3 of a stop. REALLY people? You're going to ***** and moan about 1/3 of a stop? Seriously? OBVIOUSLY, the point of the M is to shrink things down as much as possible. 1/3 of a stop throughout the focal range is a "duh" kind of compromise. As in... DUH... DO IT! (when talking about mirrorless)
If I were heading up Canon USA and I KNEW an M with a DPAF sensor was coming, I'd hold off releasing this lens. Then, when the new M with DPAF hits, I'd release it and I'd also release this lens and the 11-22.
Honestly, this lens, IMO, COMPLETES the M ecosystem (WITH a DPAF M) for the AVERAGE US consumer.
Of course, being able to add the EVF from the G1XII as well as a couple of small primes would help round things out for the rest of us.
This lens is almost EXACTLY what I was saying Canon should shoot for. A small tele zoom, even with a limited range. My suggestions were 55-150 or 75-150 and max aperture at f4 or f4.5. As long as Canon prices this similarly to their other lenses MSRP (not the street price, the MSRP) then I think they have a winner!
Nice job Canon!
Here's a quick comparison to another well known, similarly spec'd lens...
Canon EF-M 55-200 IS STM f/4.5-6.3 vs Sony E-mount 55-210 f/4.5-6.3
Weight: 260 grams vs 345 grams
Length: 87mm vs 108mm
Focal range: 55-200 (88-320 FF equivalent) vs 55-210 (82.5-315 equivalent)
Aperture: f/4.5-6.3 vs f/4.5-6.3
So, the EF-M lens is 25% shorter and 20% lighter! NICE! The focal range is a tad longer (even worth mentioning the difference?) on both the wide and tele ends of the lens and the apertures are equal - the only difference may be where the actual max aperture stops are on the focal range - I would assume they're similar but possibly not.
Also, the EOS M is 298 grams and the EOS M2 is 274 grams. This lens should balance VERY well on the M family!
The EF-S 55-250 STM is actually just a touch longer than the E mount Sony tele lens mentioned above (3 mm longer) and heavier (30 grams heavier). But, if you're talking about mounting the EF-S 55-250 to the M, you obviously need the adapter as well. You're adding an additional 28mm and 110 grams. So, here's the final comparison...
EF-M 55-200 f/4.5-6.3 IS STM vs EF-S 55-250 f/4-5.6 IS STM + EF to EF-M adapter
Weight: 260 grams vs 485 grams
Length: 87mm vs 139mm
Focal range: 55-200 (88-320 FF equivalent) vs 55-250 (88-400 equivalent)
Aperture: f/4.5-6.3 vs f/4-5.6
So, the EF-M lens is 37% shorter and 43% lighter! Obviously, the EF-M 55-200 is 1/3 of a stop slower at the wide and tele end and is slightly lacking in the "reach" department. The diagonal angle of view at 320mm is 7.7 degrees and the diagonal angle of view at 400mm is 6.2 degrees. So, 1.5 degrees. Significant... but also NOT significant.
Hope this helps to put things into perspective for some who were over reacting...