I own both the phones, N95 8GB and the E71, also had the E90 before I got the 95 8gb.
The choice is easy, in fact, there's none at all. E71 all the way.
Much much better phone, build quality is better, the OS seems to work faster than the N95, probably more free RAM as well and can take cards that the 8GB can't.
Keyboard is fantastic. The first time I put my SIM in from the N95 I thought the screen was on a smaller side - It is in terms of size (2.4 vs/ 2.8) but I think the landscape feel is much better than the portrait type of the N95.
I also had the E61 before the E90 and this phone just doesn't compare. It's more lighter, faster and the keyboard is good. It's more pocketable than all the other phones I've mentioned.
I do a lot of web on the phone and the screen is certainly better than the N95 and probably the E90 as well. (you don't need to open it up every time)
Although I'll be in the market to sell my N95 soon, all I can say is, this is much better. Let me take the hit on my N95 now