I have always incorporated isometrics into my daily schedule.
Having previously been said to be a miracle exercise, with bodybuilders becoming huge because of it, isometrics got hugely bad press when these bodybuilders were found to be taking huge amounts of steroids, and isometrics were the babies thrown out with the bathwater.

I do isometrics for my body parts, partially because I can feel it work. It doesn't matter to me that I can't see progress quantitatively, for example, the number of reps I can achieve, or the amount of weight I can lift.
I just know that my muscles are being worked hard, relative to the amount of muscle that I am building.

At the moment I'm doing dynamic isometrics to offset some of the negatives of this form of 'weights'.

Do any of you do isometrics, and if you're against it, do you have good reasons as to why?

At the moment I'm doing dynamic isometrics to offset some of the negatives of this form of 'weights'.

"dynamic isometrics" seems like a contradiction in terms. Could you explain how these exercises work?

Essentially its movement under tension. Like a cable pulley machine, you create tension using your own muscles as you move your arm through a full range of motion. Surprisingly difficult to do. Something you learn pretty quick is how strong your muscles can be, especially when you're working against them.

An example of an exercise, stand upright, and put your hands out in front of you as if you're in pushup position against a wall. Tense your body, and imagine there is a great big boulder in front of you that you're going to push. Slowly to a count of 5, push forward with your arms while exerting a force against the push with your other muscles. Now do the reverse, as if theres a big boulder bearing down on you, and you're trying to slow its movement.

The visualisation thing sounds a bit odd, but once you understand how to do it, its really easy to do.

I've tried similar programs like Pete Sisco's "Static Contraction Training" program.

I found that they are good for variety and to stress your muscles differently to avoid plateaus. However, because these types of programs arent dynamic, functional or practical (except for rehabilitation purposes) I would not do them on a long term basis.

I agree about not doing the static isometrics for long periods of time, but these dynamic isometrics (which I don't think I have explained at all well) has made me a great deal more powerful, if not a great deal more muscly, which is entirely beneficial for weight divised martial arts competitions.
I give isometrics credit for my side kicks and punches which are faster and more powerful than my instructors.

After swim season, I'm starting a routine to train the iron cross and I'll be using both isometric, isotonic, and regular weight-lifting exercises.

http://forums.johnstonefitness.com/showthread.php?t=11290

I have always incorporated isometrics into my daily schedule.

I do isometrics for my body parts, partially because I can feel it work.

At the moment I'm doing dynamic isometrics to offset some of the negatives of this form of 'weights'.

Do any of you do isometrics, and if you're against it, do you have good reasons as to why?

A negative is if you have blood pressure problems, they can worsen it.

I have used them as a diversion or supplement to weights since the 1960s. I think they build strength but can't say they build bigger muscles.