Several orders and transparent service. Make sure you read and understand the ordering process. You'll pay shipping to Canada, Taxes and Shipping to your door. It will usually end up being slightly less and in some cases slightly more than what you'll pay in Canada for normally priced items. Where they shine is in great deals and items that you can't get in Canada.
Understand the fee's your credit card charges for currency conversion if it's not USD based.
Understand the per-item cost if ordering many things directly, and if you're using them as an FFL for purchases outside IRG, note the couple hundred dollar import fee - which is also a deal, and allows you source outside IRG.
Buy with confidence, and don't worry about contacting them for clarifications (after you read the process). They'll also handle warranty for a year or under the manufactures warranty like other dealers.
Also make sure you realize they have a monthly import process, know and understand that it could be a month and half or up to two months to receive your item, depending on time of your order, time of month and the current import schedule.
Be happy when it all arrives, check back in their forums for monthly import updates.