I recall some military intelligence imparted to me in my youth: "use wireless for attack; use wired for defence."
While there are some impressive speeds achievable with the latest generation of wireless modems etc, there are always several reasons why it's not quite as good in practice as it should be. In a populated area, there may be a near neighbour on the same WiFi channel. Your laptop/iPad/whatever may be at the limit of range of the access point, and so on.
My desktop PC is wired to the router. I get 65meg down, 18 meg up pretty much all of the time. It used to be close to 80 meg down when first installed, but I was one of the first in the village to get FTTC. They've been installing it as fast as they can go, and as more and more folks have changed over, the speed has dropped. C'est la vie.
My portable things all get the fastest speed they can achieve on whatever 802.11 protocol each uses. None is as fast as the wired connection to the desktop.
My ISP specifically offers fixed IP addresses. That's useful for the VPN I use. The counter-argument is that IPv6 may be required sooner rather than later. The router I have can do IPv6, but I've not found how to get the iPad on 3G to recognise it.