As far as design goes, I think the Macbooks are far better than the Macbook Pros in my opinion - for a start, they're a newer design and Apple has had a chance to really improve upon things.
They're latchless, so you're not going to have a problem of one breaking (although due to the magnetic latches on the MBP it's not
too bad) and from the looks of things they'll close better too. (none of that "wiggle" with the lid - I've not personally used one though)
The drive is off to the right, so it's not going to warp over time like the Pros from resting on it. (the 17" anyway - my Powerbook was looking awful a year on)
Ports are all down one side, so there's no wire clutter like you get from a MBP with lots of stuff plugged in. (although I would prefer them all on the right personally, as that's where a mouse would get plugged in)
Plastic case - despite the plastic bits on the lids now, the Aluminium still interferes with wireless reception.
Less holes - on the MBPs you have holes for the speakers on either side of the keyboard - these will collect dust/dirt, and put the machine at more risk from spillages. (not that it should ever happen, but there's always a possibility) This is of course assuming you have something like an
iSkin installed.
Plastic isn't going to dent, or warp as easily, and scratches (on the white one at least) aren't going to be as noticeable. Here's my 17" Powerbook as it came back from a couple of recent trips to AppleCare:
(as you can probably tell, I wasn't happy...)
Plastic is insulated, so you can't get shocks etc off the case. The small plug on the power adapter isn't grounded iirc, and there's a tingling sensation when running my fingers / hands over my Powerbook if I use it - I assume the MBPs are the same. (I have been told by Apple that this is normal) I'll sometimes get a shock when plugging in some powered USB devices.
The Macbooks let you get into the hard drive easily, which is a huge improvement - that's the one thing that I've always hated about most laptops, as it's very awkward to get into the drive to replace it if it dies. (or costly, if you can't / don't want to risk doing it yourself)
On the plus side for the Pros - the Aluminium feels excellent to hold / use - it's extremely high quality stuff Apple is using.
The backlit keyboard is great - personally I'm a touch-typer, so I don't "need" it, but it's very useful to have, especially for things like function keys etc.
If the screen was brighter on my Powerbook, I'd also be praising the brightness sensor - as it is, my Powerbook maxes out at 111cd/m2, which is about what it should be in controlled lighting, but I'd want it brighter if I move to a brighter room etc. (I believe the MBPs
are a lot brighter, so it's probably got some use there)
Matte screen - Now, I have got a glossy LCD monitor at home, and I love it - colours are bright and vivid, and there's a lot more "depth" to the image than a standard LCD. (even compared to ones with much higher contrast ratios) They're great for watching videos/movies and playing games, but for a laptop I'd want matte, as you can't always control the lighting it's going to be in. (not to mention that I'd be using it for image editing work so I'd want it for accuracy)
As it is, I'd still buy the Pro models, rather than the Macbook, but they're really in need for a redesign in my opinion.
For a start, they really need a 13" Pro model, in my opinion. Keep the Macbook form-factor, drop the plastic for Aluminium, (while it may not look as pretty once it's damaged, it should be more rugged and feels better) give it a matte screen option and a proper graphics card, rather than onboard stuff. Backlit keyboard / brightness sensor would be nice too, but I doubt they could cram all that in. Ideally, it would have a proper DVI port on the left instead of mini DVI (or possibly HDMI as it's a smaller connector, and compatible with DVI) and an extra USB port on the right (for a mouse, mainly) if they could cram it in. That's all they would need to do, and I would buy one in a second.
I'd also want them to redesign the 15/17" Pros - latchless design if it's possible. (don't know if the Aluminium would cause it to be too strong a hold / scratch etc though) Ditch the current speaker placement, and have them on the back like the Macbooks (they still sound crap anyway, so there's no need for it) which would let you have a smooth area. On the 17" I would shift the keyboard over to the left and add a numpad - once the speakers were gone, there would be plenty of room. Move the IR sensor over to the left corner of the machine - it looks ugly next to the latch button. Have the hard drive easily accessible, in a similar way to the Macbooks.
I'm not sure if it's possible due to how thin the machine is, but on the 17" moving the Superdrive lower would be a big improvement too. (as I said above, it starts warping over time from resting on that area when using it)