Can someone explain to me why the Nem wallet is going to be browser based?
If you tell us your concerns I'm sure we'll be able to get them out of the way

I was under the assumption the client
wasn't going to be browser-based?

Again what are your concerns ?
Serving the GUI over a browser makes a lot of sense these days. It's more lightweight, easier to maintain and with all the fancy libraries in no way inferior to a native GUI.
Maybe your concerns are more directed at brainwallets ? If this is the case then it will please you to hear that our client will support local wallets.