I've been buying from B&H online for the past 25 years and for the most part, they get it right. Prices are often the lowest or at least competitive. Using their branded credit card gets me a discount equal to the tax I'd normally pay, and for me, that's about 10%. They have a pretty decent selection and they'll answer any questions, often without attitude or sarcasm.
The problems seem to occur with their shipping and shopping cart. They use the worst shipping service on the planet: FedEx. If you need it tomorrow, good luck. If you're willing to wait, your delivery window will generally be a 3-day span and they almost always deliver a day late. So unreliable. The other issue is even if you select next day or 2-day delivery, that only applies to the actual time the carrier takes, not the time it takes for your items to get picked and packed, which could take as long as 3-4 days depending on the days of the week you placed your order.
The other issue is their online shopping cart. Because they're Jewish and observe Shabbat, they close the online checkout Friday afternoon and reopen on Saturday. Unfortunately, if you put things in your shopping cart Friday night hoping to check out on Saturday, your items will sometimes disappear. Worse yet, if you add items using their phone app and later try to add more items or checkout from a web browser on another device, your items won't be there. Frustrating, confusing and poorly implemented.