Stormrazor is a bit clunky.

So, I started playing pbe a few days back, and noticed this item called "stormrazor", which gives 70 attack damage, 30% attack speed, and the following unique passive:

If you haven't attacked in the last 3 seconds (scaling down with your attack speed), gain Storm's Edge.

Storm's Edge: Your next basic attack critically strikes for 160% (+1% per 1.5% critical strike chance, max 200%) damage and grants 10% movement speed for 1.75 seconds.

And from what I've noticed playing with it the cooldown is about as long as two basic attacks. I can think of three scenarios where this item has a use, and it's generally clunky on all 3:

scenario 1: you're an ad assassin. In this case you use the minicrit the same way you'd use a duskblade or dark harvest: to deal alot of basic attack damage in one attack. In this case, the crit scaling, attack speed, and movement speed the item give are completely useless, as you won't be buying crit, and don't need movespeed just after you already engaged. It's quite an expensive item, too, at 3200 gold, so some of that being wasted on attack speed and crit scaling makes it worse value. And yes, you could use the movement speed for escaping, but 10% movespeed for what will probably be 1 sec left isn't going to help you with that.

scenario 2: it's your first purchase on an adc. In this case you use it to help last hitting. getting minicrits ever few seconds is pretty good with that, and the stats it gives are quite usefull for lasthitting. Not to mention it doesn't give nay crit itself, which would make last hitting harder (at least udner turret). The item is pretty darn usefull for that, but having to not only buy such an expensive item in the early game, but also sell it in the lategame completely negates its usefullness.

scenario 3: you're up against high mobility tanks. In this case you use it to kite them. Getting the 10% movespeed is quite usefull, and you won't be attacking as much anyway. The problem with this is that there are so many better options for kiting. Almost every crit item gives you movespeed, and for instance a frozen mallot already gives you double the movespeed advantage. Not to mention you'll be buying crit, so automaticly critting doesn't make any difference at all in your damage output. At least the stats are somewhat acceptable, though you'd have to give up another ad item, and at the moment, that's not worth it in the slightest.