I like shopping online for some things such as books, for example, but ever clothes or shoes. I have to try those on and don't like losing the postage money if they are not right.
Electronic things I would only buy online if it was a great bargain, as if they go wrong its more of a hassle to send them back.
Generally I only buy online if it's something I can't get in the shops or it's cheaper. I live in a place with good shops though, so don't do if that often.
One pro is the convenience - not having to bother going anywhere, but a con is inconvenience - not actually being therev when it turns up and having to collect it from the post office depot!