Well I haven't had this phone for that long yet, but so far it has kept on disappointing me. My use may be rather specific though.
I came from Windows Mobile where you can pretty much do anything of the time. I've grown out of apps and don't really play dinky games, but I'd still like to have my phone have options that are readily available when needed.
The first thing is that Internet Sharing doesn't work. I bought a GoPhone and thought it was AT&T, but now got an unlocked one and it still doesn't work. They put my SIM in a brand new android and it worked right away! And I just found out that MS locks the WiFi API so there's no such thing as WiFi Analyzers for WP. This is one of the more useful Apps when you're dealing with anything WiFi.
Overall, it seems MS is trying to "iPhone" themselves and pretty much hold your hand and not let you cross the street unless it want's you to. It's a big change from the attitude they used to have, where their devices were meant for "industrial tweeking". Now they are just trying to go for the mass market appeal and ignoring customization because they just want to tie you into themselves even more...like that fruit company.