I got to open mine up late last night and go through all his transformations once. Initial impressions, starting with my biggest nits to pick:
I'm really disappointed in Leozak's jet mode. We're used to the standard jet transformation at this point: bot collapses into the undercarriage junk while the jet mode unfolds on its back. Leozak is similar, except he really doesn't collapse. His arms just sit there, which isn't too unusual. But instead of collapsing his legs, he just has a couple flaps swing up from his calves to hide his thighs from above. Worse, the combiner shoulder connectors that sit next to his feet swing out to stick out the back end, and don't even really do anything to make them look like jet engines. The result is a really stretched out and awkward jet. That's disappointing since I've always loved the F-14 and was really looking forward to adding another one to my collection.
Deathcobra feels like a bit of an afterthought, which isn't too surprising for a stretch goal. He's reasonably good, just not as good as the rest. His propeller is awkward in every mode other than helicopter. Cannon mode is underwhelming, and sticking all the guns on him isn't something I'm too impressed by. The lack of a seventh spear is also disappointing. I'm still very happy to have him, just wish he were even better.
I'm mildly surprised they didn't decide to make him compatible with the frame combiners. The limbs all attach via the same basic methodolgy, so it certainly seems like they could have done so easily enough. Honestly, I want to go try the arms when I get a moment. The legs are obviously not compatible, but I realized later that it's only an assumption on my part that the arms aren't also.
Joint tightness varies joint to joint, but nothing outside normal tolerances. The leg guys' toes are a little tighter on mine, but nothing abnormally so. Really, just has that new-toy joint effect of needing to break it loose on first movement. No QC issues.
I'll second ZacWilliam about being surprised by the size of these guys. In bot mode, they're right around the same height as other modern combiner limbs. However, that doesn't account for their bulk, which really comes across in alt mode. The jets are substantially larger than the Aerialbots in jet mode. The legs feel massive in alt mode. Unboxing them in alt mode, they feel more on par with the SS86 Constructicons than the other current combiners.
I absolutely love all the partner figures. They're simple, but they do exactly what they need to. I wish there were a leopard to complete the big cat set. The breastplates are better integrated into the ground vehicles, while they just peg in and hang out in front of the aerial guys. On the flip side, the flyers still look complete when they're removed, while the ground guys look like they have a giant hole in their chests.
Beyond that, they're all really good. Bot modes are all great. Alt modes are nothing spectacular, but mostly good. Liokaiser himself is really solid and looks great. Other than Deathcobra's participation not being on par with the rest, my only quibble is that Jaruga's arms don't securely peg into Leozak. I might use some nail polish to tighten that up.
Basically, I'm really happy with him. Not perfect, but really good.