For what it's worth, I've had a go in a Peugeot 107 - the same car bar badge and bumpers as the Aygo. I borrowed one for a night - it was amusing enough as a novelty, some aspects of the design are really clever, and the handling was amusing but I think practically living with one would be a bit of a trial. It was pretty noisy, and there wasn't much space in the back (the boot is far smaller than my memory says a 205's was). There's also very little space to actually put stuff in the cabin, which would annoy me. However, if you just want it for around town and short journeys it might suit well - it depends what you want it for.
If you do want one, it's also worth shopping around between the three manufacturers - they all come out of the same factory, so there's nothing to choose between them for build quality & reliability, but the Citroen/Peugeot versions are cheaper (and are likely to have much better customer offers). Of the three, the Citroen's the cheapest as list price, but with their cashback offers a C2 is actually cheaper - another alternative! It's also worth looking at the spec - initially there doesn't appear to be much in it, but by the time you've got something with central locking, air con etc they're not quite as cheap as you might expect.
In terms of Clios, until very recently mine was a two-Clio household (a Renaultsport and a dCi 80), and they were both absolutely great. My girlfriend gets over 60mpg from her Clio on long run - not even a Cappo can do that! But then I do work for Renault, so I may be biased!
Other alternatives to consider are things like the Kia Picanto (much roomier than the C107ygo, and has 5 doors), the Diahatsu Sirion (Diahatsu are owned by Toyota, and I've read some very good things about the new Sirion), the C2, the Ford Ka, and, of course, the new Swift.
I've made the assumption here that you want to buy New - of course, if you're looking at second hand, that opens up a whole wealth of alternatives!
Sorry - I've just reread this and it's become something of an essay. I hope it hasn't confused more than it's helped!