Portability 

I've had a chance to use this lens in a good few situations.  When walking around, the lens coupled with my EOS 400D, is fine for carrying with the shoulder strap. It's a little heavy, but not to the point of being uncomfortable. I can happily cart the two around all day.

Lens Hood 

The supplied lens hood negates the need to replace the lens cap. It provides adequate protection on its own, has never been knocked off, and is a good solid fit.  Glare from the sun is greatly reduced by the hood, which has plenty of depth.

Handheld or Tripod? 

I find that I can keep the camera nice and stable in my hands, same as I can when a small lens is fitted. In good daylight, shutter speeds are nice and fast, which allows for handheld shooting right up to 200mm.  I've also been shooting handheld landscape shots at sunset, without any need for a tripod.  As is the case with pretty much all lenses, a tripod is highly recommended when taking close-ups. Although, acceptable results are possible without.

The f/4 aperture is nice and wide, and is useable right up to 200mm. It's not the fastest lens, but is fast enough. If you need to shoot in low light conditions, the f/2.8 version of this lens would be worth a look.  But, don't waste the extra money, unless you really need that f/2.8.

USM Auto-Focus

When in AF mode, the lens is pulled in to focus by a reasonably fast ultrasonic motor. There are no whizzing or whirring noises with this type of motor.  It is not totally silent, however. The lens parts do make a slight noise when they move.  It's not the type of noise which attracts attention from wildlife.  Wild birds seem not to be startled by it.

There is a switch for AF or manual focus, on the lens enclosure.  Alongside that, there is another switch to set the minimum focusing distance. The choices are 1.2m or 3m. When set to 3m, the lens should focus a bit faster in AF mode. I have no way of accurately testing this, so we will just have to take Canon's word for it.

Image Quality

Given that the lens elements are the best glass available, image quality is spot on.  Colour requires very little, or no correction during editing. In particular, bright fluorescent colours are reproduced very well.  I was finding that brightly coloured objects, such as buoys, were looking bad when using the cheap Canon kit lens.  That problem is now history, with this EF 70-200mm f/4 L USM lens.

Sharpness is very good too. So long as the focusing was good, photos can be tightly cropped at 100%, with sharpness left in tact.

Chromatic abberation, those nasty coloured fringes, are near enough eliminated with this lens. I've only noticed very slight CA on very few photos, which were taken in difficult light.  I don't expect a good photo could ever be ruined by CA, when using this lens.

All said and done, the quality is what I had hoped for.