IS is NOT essential for handheld work. If it was you'd be denying the existence of 100 years of documentary film-making. Desirable, yes, essential, no way.
Steve

I think Ian meant essential with regard to the 550d, which is very small and light, which as we can all agree makes a big difference to camera stability.

The documentary filmmakers used heavier, more ergonomic cameras. Even with a rig on a small DSLR, IS makes a huge difference. Try shooting with a bare 550D/T2i with and without IS - you'll know see for yourself.

Most of those documentary films makers didn't us a camera with a CMOS sensor.

That isn't a judgement or endorsement one way or the other, but any shaky movement can ruin a shot with these camera's. Its just one of the limitations that we have to learn to deal with and IS can make a big difference.

OK, I take your points. Still correct to say that it's not essential, but good points.
Steve

I sometimes use IS on telephoto lenses, such as the 300mm L, but always prefer to use a tripod for most footage. The onboard mic picks up every single squeak and click of the lens, so I'm glad that I use a dual sound system so that I can concentrate on the shot.
Even in situations where I'm not using the Zoom H4, I completely ignore the problems of the IS lens sounds, knowing that I can easily overdub with separate natural background sounds or narrative or music dropped in to the time zone.

With wide angle lenses I never use IS, and prefer just a steady hand for when I'm not moving around too much, or a tripod when I'm completely static.
When I need to move around a lot more than a static tripod, then I'll mount the camera on my Samcine shoulder & waist brace support - which also helps with smooth slow pans or when I want to move positions during an interview, etc.
For smooth walking/running footage, nothing beats a steadicam (I like to use the Hague HCS-Pro with the 5D Mark II, which works great for very smooth 'fly-through' footage, even on hilly outdoor terrain).

IS lenses
 

Anyone have any luck with the 18-135 IS lens for video? Certainly an inexpensive lens compared to the L series for sure but just how good/bad is it? Is it tolerable?
Use will be only for outdoor wedding video work.
I have access to L series lenses other times from my other still cameras...just not when I'm shooting a wedding. I would prefer not to have to buy another expensive zoom lens only for weddings.
Thanks, Craig