The new Wave is quite a bit different than the old one. The tools are one-at-a-time unlike the old one where you'd try to pull out one and they'd all come out. Plus, they all lock. Instead of the phillips driver, you get the bit holder, but just the one bit. They also put phosphor bronze washers in the blade pivots to make things smoother.
There's 2 Charges, the Ti and the XTi. The differences between the two can be seen on their website. Assuming you're looking at the Ti (which keeps the scissors, but only has 1 bit holder), it's very similar to the new Wave. I can tell you that the handles are much more comfortable with the Charge when using the blades, since they're thicker and rounded off (the Wave digs into your hand). Don't worry much about the titanium scratching much, since they're orangepeeled and'll hide scratches well.
The biggest differences though between the Wave and the Charge are the the main blade and the pocket clip. The pocket clip FINALLY lets you carry your leatherman as an EDC without requireing the sheath or having it bounce around awkwardly in the bottom of your pocket. And of course, the main blade is made from premium 154CM. All the other tools made by leatherman (regardless of model) are junko-quality 420J :barf: (except the interchangable bits, which are S2 tool steel). OK for light use blades and other tools, but if you're carrying the knife as an EDC (again, thanks to the pocket clip), the 154CM is a huge boon.
Plus, with the charges, you get an excellent 4 position sheath (normal vertical plus horizontal) sheath that not only holds the knife, but also the bit holder with a bunch of bits. The bit kit is extra with the Wave (and buying the Wave with the bit kit costs about the same as a Charge

).
I chose the Charge XTi over the Ti because I already have scissors on my Squirt S4 that I keep on the keyring. I don't carry my Charge like a knife though, it stays in the sheath and I keep it in my backpack.