It's really not very good. There is no kinetic panning, zooming in and out is not the smoothest experience, it can be slow, etc. The worst part IMO is that often it will not pan if you drag over the website but select text instead (this happens e.g. on CNN.com).

On the upside, there are replacement browsers you can install, and from what I hear, they are not so bad... Still, Safari probably has better usability.

You do sound like someone who could enjoy the tablet, but switching from an iPod touch might be a shock. Imagine going from Mac OS X to Windows 95, something like that. You may have more power on the hardware and more capabilities, but the out of the box experience won't be nearly as pleasant.

The new device will be considerably different though in some ways, so if you like the idea of the tablets as they are, it might be a good idea to get one now to get a better idea of whether you will like the new device or not.

If you are only interested in a truly polished user experience, I would recommend to wait for the new device and then base your decision on what you learn about it.