Yes, the e7 will work on pretty much any frequency in the world, gsm wise anyway. I have both, e7 is entirely different from n900. I love my n900 more than anything, but e7 does a few things better, notnsaying it is entirely better, just these are the things it does better:

Maps nav
Hardware, metal, glass, amoled, and yes even keyboard
Phone and gsm network functions
Contact mgmt, mainly all the fields
Battery life

Other than that, I use my n900