Looking for the one piece that you lost that is hard to find? Need to get a new set of stickers for that set? Want to buy a large amount of 1x2 red bricks? Looking to get a mint condition set no longer available from stores or from LEGO? Have you tried Bricklink.com? Never heard of it, let's review it here.
Price: You'll find a huge price range on Bricklink.com. Individual sellers to bigger stores selling new and used items. You need to do your research before you buy. Make sure you're getting the best deal available. Some stores charge packing fees, handling fees, PayPal fees, or other random fees. Read closely and pay attention. Feel free to ask questions of the sellers prior to ordering to make sure you know what you are paying for.
Product Availability: If you can't find it on Bricklink.com, it probably doesn't exist. Search carefully. Sadly, some sellers put fake items up so be careful at what you see. If it looks too good to be true, it probably is.
Set Selection: See product availability in terms of the selection. The issue with Bricklink.com is that it is not user friendly. Items are coded in using LEGO's set and piece numbers. Searching through the monstrous database can be a pain. The items are there, you just have to find them.
Shipping: Most sellers ship pretty quickly. If they do not ship quickly comment as such. You can request overnight FedEx or get the slowest USPS shipping at the cheapest cost. For the most part shippers package items so they are not damaged in transit.
Customer Service: Bricklink.com runs on comments. For each order, you will have the opportunity to post feedback on the seller. They in turn will rate you. In theory this keeps everyone honest and the system working properly. There will be some bad eggs in the system, but you can read their feedback to determine if you want to work with them or not. Be cautious of new sellers. They may have no feedback posted or very few posted. In theory their prices will reflect the limited comments.
Overall: Bricklink.com is a marketplace focused mainly on dedicated to adult fans mostly. It can be a challenge for those not into the LEGO hobby to use the site. The buyer should beware and do research on the items they want and make sure the seller they choose to use has a good reputation in the system. It can be a great place to make purchases though. Especially if you are looking to find a lot of parts and pieces cheaper than buying them brand new from LEGO's Pick-a-Brick.