I have finally managed to 'test drive' the new DC24 and DC25 in one of my local shops and also spoke to the UK Dyson helpline about them too.
Test drive:
DC24:
Very light and compact (lighter than the DC22 canister!) and easy to store! The handle release on these new 'ball's are easier to use. In use the DC24 is not too noisey, very light and easy to steer. The brush bar spins very fast and you could see it and partly feel it grooming the carpet (although the carpet in the shop was short pile I believe). The brush turfs on the DC24 are thin but not that spaced too far apart. The actual brush barrell is very thin which I suppose you can expect for the size of the machine and head. There is a reset button on the brush bar head like the DC18. The brush bar is all one peice again powered from one side. You can turned it off like other modles for hard flooring etc.. Tools, you only get a new version of the combi tool. The wand does extented like a mini telescope wand. So you have the main metal tube plus a plastic one that extents out! For the size of the motor/air watts the suction for it's size is not bad.
DC25
Again very light for it being a 'full' size Dyson. Again the handle release on this new 'ball' model is easier to use than the previous DC15. The wand works like the DC18 and the US DC17. Pull it out from the top and the handle automatically releases from the machine. The hose stretches to the same length as other models and is longer than the original ball DC15. Tools on board, you get a new version of the combi tool very square in shape so is the new stair tool too. In use the DC25 is very light and easy to steer! Again the brush bar spins very fast you could see the brush bar grooming the carpet (same as use with the DC24 above). Coud not see any reset button. Again the brush barrell is one peice. You could feel the suction power and it grooming the carpet (in fact it felt like it was hugging the carpet!) better than the DC15 and DC18. But it was still easy to steer and move over the carpet it felt light. The brush turfs on the DC25 were more spaced out than the DC24 but where thicker brush turfs and slightly shorter. No metal sole plate on this model which I think they should have put on. The suction power is very strong probably on par with the DC18. Filter wash intervals every 3 months compared tot he DC18 (and others) every 6 months! Why this is I'm not sure as the bin setup is the same as the DC18. One thing I noticed which has been commented on here is the noise the DC25 makes when you turn it off. Not sure how to describe it but it happened.
Change over valve DC24 and DC25
Not sure if anyone has noticed but the change over valve on these 2 new models is different from other Dyson uprights. Normally this happens when the main body of the machine is lowered or return to the upright position. The valve moves to either the floor nozzle when body is lowered or the hose when the body is returned to the upright position. Not on the DC24 and DC25 the suction/air flow is directed at the floor nozzle all the time until you release/pull out the wand the change over valve switches to hose. On return of the wand the valve switches back to the main floor nozzle. If you look on both modles at the base of the hose one end of the wand pokes out pushing a flap open which closes if the wand is removed. This flap is spring loaded and this is what moves the air flow from floor to hose when the wand it removed or replaced. That is why they have used a flexi hose just before the airflow enters the bin. You will noticed the end cap on the DC25 does not have vents in it anymore, this is why. The DC24 still does have vents in the ned cap,
Overall
I would probably go for the DC25 if I had to choose. I think the DC25 is a vast improvement on the original DC15 Ball. I do feel the bin though could have been taller not necessary wider in diameter. I was impressed by the DC25 which when I first saw it though it was just going to be like the DC18 but with a bigger ball!
I not sure why some of the UK shops I've been in have dropped the DC18 Slim over these 2 new models. One thing the DC18 offers but both these new models can not is the slim body which allows the main nozzle head to be wider than the main body of the cleaner. Although they both have slim\small bins like the DC18!
Dyson Helpline
I called the helpline for another query but questioned them on the new DC24 and DC25. I was told these cleaners are something completely new to what Dyson has done in the past. They are lighter and easy to use and steer. One thing I was surprised to hear was about the airwatts and performance. I was told that Dyson has always gone by airwatts and not motor wattage but with these 2 new models they are going against what they have always said in the past and in fact these give the same if not better performance. The reason for this I was told is due to the (yes we come back to that subject we all love!) new motorised brush bar. Unlike the belt driven (referring to the DC07 and DC14) which uses the main motor, driven by a belt these new models have motorised brush bars that spin faster than the belt driven ones, that fast you can hardly see it moving!. As most of the work (cleaning) I was told is done by the brush bar (2/3 or 3/4 can't remember which one I was told!!), becuase the new models are more effective they don't need as much suction to remove\carry the dirt away. I have to say the DC25 brush bar does spin very fast and does groom and hug the carpet better than the DC15/18. I was impressed with the DC25. The DC24 and DC25 I believe are belt drive by a separate motor unlike the DC15/18 which where geared driven motor, correct me if I'm wrong!
Other Comments
I've noticed on the UK Dyson web the accessories for the DC24 and DC25 are now showing. One thing I've noticed a new stair tool for the DC18 is £9 but for the new DC25 it is £2.50! Why!? Probably due to the shape! Also on the DC24 you can get a new main nozzle head for £65.00, nothing showing for the DC25 as yet! So looks liek the head on the DC24 comes off like the DC18 does!
I think that is it! Just thought I'd share my findings!
DC18