Centerpull's, in terms of mechanical design alone, are a more reliable mechanism for transmitting equally leveraged braking force to both sides of the rim concurrently than standard design sidepulls are. In that regard (and most regards), they're really much better.

It all starts to all apart a bit when you get to the downsides. Centerpulls typically weigh more, require cable hangers (which can't be too flexible or they'll compromise action and power), are typically more complex and there are more adjustment points for proper setup (which requires more mechanic hours $), require a longer pull lever and so, typically don't feel as solid upon application. C'pull arms are typically spread wide to allow for best tire clearance and rim removal and wider stance forces the pads to connect with the rim farther along the pivot swing arc. This tends to wear the pads unevenly and and requires mindfull adjustment to compensate as the pads wear (more mechanic $ and though this really applies to all bicycle caliper brakes, it's more of a problem with the wider stance C'pulls require)

Dual pivot sidepulls, which successfully mimic centerpull mechanical action, simplify most of the setup problems with C'pulls though they're typically still heavy, just like c'pulls .

Modern incarnations of the dual pivot concept, like the Ti2 racing, KCNC and the EEbrake are some of the most interesting designs in the pantheon and give riders the best of both worlds (though they'll look a bit strange on your vintage Peugeot). Paul's Racer brakes are an interesting modern, summation to strictly centerpull evolution as well.

Danny