Mine arrived last night, and my Black Widow weirdly seems to click into place much lower than the prototype images. I'm guessing mine's mis-assembled aswell. It does push up further to where it's shown in the official images, but it takes a damn sight more force than should be legal on clear plastic. A fair few people complained about dodgy rotations on the lower legs that didn't quite lock, and that the grapple hook didn't tab into the back or the abdomen tightly, but I've had no such issue, thankfully.
She looks great though, hanging out with Takara Generations Waspinator, and especially hanging out with Beast Wars Quickstrike, the transparent yellow-orange plastic comes out real nice. Finally took my junky TM2 Black Arachnia down from my Beast Wars display. She's up for sale if anybody's looking.
My Nightbird suffered a few QC problems as well. Her neck doesn't like to tab together properly, and she seems to have a lot of plastic flashing around the edge of the mantle/neck piece that is preventing it from rotating back all the way so that it stays clipped into the back of the torso with the tab on the back of the neck. I had to take a craft knife and try and gently shave it down a little, and it's much better now, but I've ended up with scratches in the silver paint on her bust

. I modded the hands so she can hold her swords reverse grip. I realise I've probably devalued the figure by doing it, but after having scratched her paintwork, I didn't see that it mattered anymore.
Of the 3, I have to say that slipstream is my favourite though. She's much tighter everywhere than Takara Windblade was, especially in the heels. They've stayed in place and not slipped out once. She can convey a lot of sass when she's posed right. It's just a shame that posing her is limited somewhat by the neck and the hip joints. Her and Nightbird are now hanging out with my Season 3 and beyond Decepticons.