I purchased my first Glock, a Gen 4 G19, just last night. After I brought it home, I thought it would be an interesting comparison to my Kahr CW40 (my primary carry gun). The two are amazingly similar in size given the additional capacity of the G19. Fully loaded, the G19 weighed 8 oz more than the CW40. Keep in mind, the G19 holds 16 rounds (one in the chamber) whereas the CW40 holds 7 (one in the chamber). Granted, the .40 caliber rounds are each slightly heavier than the 9mm rounds.
Width and barrel length are the two advantages the CW has over the G19. The barrel is, perhaps, 3/4" shorter and the slide and grip are perhaps 3/16" wider. This is based purely on a visual comparison of the two weapons.
Kahr lists the width of the CW40 at .94" on their website, a height of 4.62" with an overall length of 6.36". Glock lists the width of the G19 at 1.18", a height of 5" and the slide length at 6.85". In my visual comparison the height of the Glock seemed to be less than that of the Kahr (with the magazines inserted).
Now, I haven't had the opportunity to carry my G19 yet (still waiting on delivery of my CrossBreed holster) but it seems like a highly concealable handgun that should handle very much like a service-size pistol.