It's legit, but you have to look carefully at the photos they provide and read the descriptions - all of the products are not created equal, so if you want an authentic Ego, for example, make sure it says "authentic Ego" and not "Ego style" ("____ style" is fasttech speak for "clone" or "knockoff". The same applies to, say, kanger protanks... they have "authentic protanks" but there are also a few pages of "protank style" tanks. Some are good, some are not - read the descriptions and check the discussion threads before you take a punt on a "____ style" anything. Some of them are worth every penny and some are garbage, but the discussion threads will steer you in the right direction if you're not sure how to tell which is which. Not sure I'd want to risk knockoff batteries unless they were just for cheapo backups, though - but that's me.
Pay attention to the stocking information right under the listing... it will say "in stock" "ships next day" "ships in 5 days", etc. If it says "ships in X days" that means it will be that many business days before it starts the shipping process.
From there, it usually takes a week to get from China to the US and another week or so (including time sitting in customs) to get from its landing port to me.
If you're ordering external batteries (like 18650s) be prepared to wait *months* as those have to clear customs in Malaysia and at the moment they have a massive backlog (the better plan is just not to get external batteries from Fasttech, for now).
I've heard conflicting reports about internal batteries like Egos, itaste vv3, etc. Those don't have to go through Malaysia, they can go Singapore Post, but some people have reported customs delays there too... and some have experienced no real delay.
*My* comfort level at the moment is just not to order anything containing a battery from fasttech until they get things sorted. Either way, you will get your items, but if there are batteries in your order, it may (or may not) take a while.
For other random stuff though - mods, attys, tanks, coils, etc... it's about two weeks for me.