I've signed up for a Pilates course and have just got back from the first one. I don't know what to make of it yet - has anyone else tried it and did you find it beneficial?

I've done 2 seperate courses with 2 different instructors.  Enjoyed them both 'cos it's not sweaty stuff, but honestly didn't feel any benefit. 
Daughter who is an Osteopath recommends it for core strength.  Maybe I didn't stick at it long enough.....

Can someone tell what exactly Pilates is and how it differs from the old style exercise?Thanks.

It's stretches and holding positions while breathing correctly so focussing on specific muscle groups rather than flinging yourself around.

I do it and find it really helps with my flexibility and posture. I'm doing a course aimed specifically at horse riders, so we do a lot of work on the gym balls, balancing exercises and using specific muscle groups independently (eg turning hips without shoulders and vice versa). I am quite fit in a cardio-vascular sense, have good stamina and am quite strong, but have never been very flexible and have always had tight hamstrings/quads (from riding) but am now far more flexible. I am also quite round shouldered and have noticed a big difference in my posture (opening up my shoulders) since doing pilates.

Make sure you go to a small class where the instructor can check you are doing the exercises correctly - very important especially if you have any sort of back problem.  It is extremely beneficial if done correctly, i.e. ensuring you are using the correct muscles for the exercise.  Not pliates I know, but for example when I go circuit training and there are hip extension exercises I often cringe at how people are doing them by arching their back and flinging their legs upwards...

Quite a lot of physiotherapists are qualified to teach pilates so if you decide you are having no luck with the class you are attending (not suggesting this to be the case) this may be another avenue to explore.

Our instructor is a chartered physio - for horses, dogs and humans. She normally teaches pilates on a one-to-one basis for spinal rehab patients, but is doing small classes for us riders.

I've got to find a Pilates class. Have done them in the past but the exercises always hurt, so my recent physio said that they aren't a good instructor if they won't adapt to your injuries.
Was told to make sure the instructor is a trained physio.
I think it will take a bit of time to notice any difference, but i was told to go due to my posture and that i really need to improve it!!  I can't see by doing it is going to be negative to your body..
Enjoy them

> Was told to make sure the instructor is a trained physio

It doesn't have to be the case, but as they said make sure they pay close attention to you and can adapt and change things as necessary.
I'm forever telling people to try pilates, maybe I should practice what I preach....