I bought my X10 as a 'I can't be bothered taking the 1d' occassional use camera. It fits this bill perfectly. It is a frustratingly clumsy camera to use, AF is lousy, optical viewfinder is practically useless and the controls on the back are horrible. Despite all this I love it! It's weird. It does force you to slow right down and take your time, but you can set it up perfectly for street photography especially if you use zone focusing. I don't bother using any of the special EXR functions at all, some get good results but I prefer a more 'old style' approach. I often have it set to jpeg only rather than utilising RAW, mainly to force me to get it right in camera rather than relying on PP, it is afterall just for fun.
I would seriously recommend you buy at least three spare batteries (they're about a fiver from Amazon)
Anyone thinking about this camera I would say provided you can see past the limitations/faults then you will love it. There has been a lot said about the sensor and the infamous 'orbs' but I have yet to have this problem. Even if they do show up at some point I'm not fussed as for what I use the camera for it wouldn't matter in the slightest.
If you get one, buy a half leather case for it (you can get faux leather ones for about a tenner, they're actually rather good) and it will transform the handling of the camera. People bling them up with special (and very expensive) grips and 'soft shutter' buttons and so on. Not sure why but each to their own.