I have an Xperia Mini; I like it a lot. It’s phone sized rather than where-the-hell-am-I-going-to-put-this-large-brick sized.
It has a GPS, it runs Alpinequest (what I use) or whatever GPS enabled app you care to use.
The only downside I’ve experienced is a fairly major screen sensitivity issue… it seems quite common that as the phone gets warm the screen starts going mad, including the “back” and “menu” buttons at the bottom. Mine was fine for a month or two but then this problem got steadily worse until it was basically unusable if I had had the phone in my pocket or had been using it for more than a few minutes.
It is fixable if you take it back to wherever you got it from and get them to get Sony to adjust the screen sensitivity; or if you’re confident with this sort of thing there are instructions on t’intarweb on how to root it and fix it yourself. I did the latter; it’s been fine ever since.
I would still get the phone now, but I’m amazed Sony haven’t done anything about this problem that seems fairly common and mades the phone frustruting to use or totally unusable…