The Plot: Aliens try to create a new Ice Age, counting on Seven's weakness to cold to hand them victory. While the episode is nicely paced, the basic premise seems flawed. I doubt Seven should have much problem with cold if he flies through the vacuum of space on a regular basis. In the end, it only seems to slow him down a bit anyways...even in human form.
The Seijin/Kaiju: The Pol(sp?) aliens are REALLY lame...poorly designed and executed marionettes.(At least they didn't have the absurd voices from the TNT dub.) They keep appearing to Dan as if in a dream...so I'm not sure if they can teleport in at will or if they are communicating with him telepathically. Gander, their pet monster, on the other hand....looks good. A decent design that actually doesn't looked slapped together at the last second. The monster also has a point to being in the episode...another plus.
The SPFX: Pretty good, though the scenes with Dan are obviously a set.
The Other Stuff: As mentioned above, I doubt ANY Ultra being would have a ton of trouble with cold beyond maybe slowing them down a bit. They fly through the vacuum of space, use energy weapons, and may be composed of living energy themselves. Cold...uh...ok. Also, the temps listed in the episode would have killed the humans in the episode in a short amount of time given their lack of protection. Overall, I liked this one. Yeah, the plot has a big hole, but the execution is nice, especially compared to the last few episodes.