The great thing about buying local is that you can simply go to the store and check it out before you actually buy. If you do not like it, then it is very easy to just walk into the store and return.
The negative about buying a laptop online is you must wait for it. If you need it immediately, then 1 day shipping (after your order is processed) is going to be very expensive; likely $150 or so. If you do not like it then you need to call for a RMA authorization because online stores will not accept returns without one. Lastly, you may or may not need to pay return shipping; sometimes return shipping is covered by the online seller.
The benefits of buying online is that you have a wider selection, and you can also find pretty good deals. The bad thing is that you cannot physically play around with the laptop before buying it. Say for example there is a 13.3" and a 15.6" laptop that you like and both have 1080p screens, but you are concerned that texts on the 13.3" laptop will be harder to read than on the 15.6" laptop. You would then need to go to a store and look at similar laptops to gauge if the 13.3" laptop would be fine.
If you buy directly from the manufacturer (Dell, HP, Lenovo, etc) then you can actually customize the laptop to your liking if they provide that option. Some laptop models can be customize, while others cannot.
For example, over the summer I ordered a ThinkPad T530 directly from Lenovo's website. I customized it with a 1920x1080 resolution screen rather than the standard 1600x900 resolution screen and a couple of other things as well. All Lenovo laptops originates from China and I simply selected "standard shipping" which was included in the price. ETA for delivery was 10 days after my order has been processed. I think it was delivered in 8 or 9 days. After getting my laptop I immediately noticed it was not the configuration I specified. Lenovo gave me 2 options:
1. Return for refund (all newly ordered laptop have free return shipping)
2. Exchange the laptop for properly configured one (I send back the current laptop, Lenovo ships the new laptop)
Since I did not absolutely need a new laptop and Haswell generation laptops were going to be released soon I decided to simply return it for a refund. Still on the prowl for a new laptop, but again, not absolutely necessary at this point in time.