I'm including the time you have to wait for the package to come, and potentially getting something that doesn't fit (and if it is something you need, additional time to send back and wait for the new one) as a hassle.
Here's an example. My son had to get a suit for his 8th grade graduation. We were wandering the mall looking for something reasonable when I said, hey, why don't we just look on amazon? Sure enough, the exact color he wanted was there, and it was cheaper than anything we found in the mall. We went ahead and ordered it. He was going to wear it twice, so I wasn't overly concerned with the quality. It comes a few days later, and he tries it on. The jacket fits, but the pants are too short. So, we have to end up ordering a second suit to get the right size pants. Another few days wait, and of course this ends up being one where it doesn't come by the "guaranteed" prime shipping date so there are a couple of nervous days where we are just hoping it comes by the day he needs it.
Ended up working ok, but I consider all of that a hassle.