The big breakpoint with Bloodstorm Blade is 4th level. That gives you Lightning Ricochet for thrown full attacks, unlike a returning weapon which doesn't come back until the start of your next turn. You also pick up Martial Throw (use strikes with thrown weapons) and Thunderous Throw (swift action to treat thrown weapons as melee attacks for the turn), plus a bonus fighter feat for good measure. Since Bloodstorm Blade doesn't grant any maneuvers nor full initiator level progression (only the normal 1/2 level for multiclassing), you really need the class features to be worthwhile, and they just don't stack up.
There isn't that much of value at higher Bloodstorm Blade levels. Blood Wind Ricochet is a full attack that you have to split across multiple targets and that costs a readied IH strike, with the minor but interesting benefit of bypassing cover and extending range by ricocheting off of other targets. It's an interesting option, but you can't attack someone with total cover relative to you, so no ricocheting to strike around corners, and you're splitting your damage across multiple foes. Eye of the Storm lets you eke out an extra melee attack as a swift action by provoking an AoO, but that competes with the swift action you need for Thunderous Throw to make your normal thrown attacks into melee attacks. Plus, you need to get into melee range (as opposed to your preferred M.O. of attacking at a distance) and provoke an AoO (granting your enemies the same extra attack that you're getting). Blood Rain is 3 extra damage per round (not per hit, just per round), which is typically less than what you could get from the stance it replaces, such as Punishing Stance's 3.5 per attack. Blade Storm is neat if you're fighting swarms of enemies, at least, as it's basically an AoE attack, but it's still just a single, regular, non-strike attack.
If you plan to focus on poison, make sure to pick up some method of rapidly reapplying it. By default, a poisoned weapon stays poisoned only for the first hit. That's part of why it synergizes so well with thrown and projectile weapons; if you use a different weapon or piece of ammunition with each attack, you can just poison them all in advance. However, that's something that Bloodstorm Blade tries to avoid. It's most important class feature, Lightning Ricochet, (and many of the features it has beyond that) is all about letting you make multiple attacks with the same weapon.