[Q]What are the effects of using a lower amperage charger on the battery?

Lost the stock charger and found one with exactly half the ampere output (500mA)
Since, the amp output difference, really big, I am noticing longer charging times. And even longer, while browsing on mobile networks.
Would continuous charging, with the 500mA charger,recommendable?
I mean, wouldn't be any problem, if the device not able to draw adequate Amps?
I usually, use the device while charging. Usage includes both gaming and browsing.