BHPhotovideo is reliable and has fair prices - I have been using B&H for years and have purchased everything from betacams from them to professional DSLRs. Here has been my experience with them.
Pros:
They are extremely reliable in their shipping and they always have US warranties. They never sell grey market goods and you always get brand new products. Their customer service is excellent and I have been able to both exchange and return products to them without any problem at all. I bought a JVD HD cam from them and noticed a single dead pixel and they exchanged it for me without any problem at all. I have purchases lenses which I thought were soft focus, and those were also exchanged without a problem. They do wait until they receive their old product before they give you a credit, but that isn't much of an issue.
Cons:
Their prices are fair, but they are never the lowest around. You always pay for shipping and they never have special deals or coupons. If you shop around you can almost definitely find whatever you are looking for cheaper elsewhere. They offer no return incentives or email coupons for good customers. Even other mainstream stores such as Dell or Amazon may carry the same item for less because of shipping and special coupons available online. I typically check around a little bit before buying from B&H, and if the price difference is great, I may sacrifice the B&H excellent customer service for a better price.