I've owned an Aygo. Did over 30k in 18 months. Engine very reliable, servicing cheap and consumables cheap (tyres, breaks, discs etc). Some fun can be had nipping around and it can be chucked around a bit, but don't expect much.
Build quality across the range is very poor, interiors are basic, seats uncomfortable on longer journeys.
If that 07 one hasn't had a clutch already it will need one soon. Ones pre 2009 are renowned for failure, early as well. The Mrs has a 58 plate one and that had a clutch at 27/28k - a baby. On the upside, uprated clutches are cheap (190mm diameter). If you do end up doing one, make sure the whole lot is done - clutch disk, pressure plate and throw out bearing. Will only cause issues later on.
Lost very little money on my Aygo over the time that I had it, not something I would buy again and will be ensuring my Mrs does not buy another. Would happily pay extra for more.
Oh and if you have the air con switched on, you loose a lot of power. Considering it doesn't have much, it can be embarrassing wondering why you're not moving, particularly on faster roads!