[*] Probably the lowest prices you can find outside of individual sales, especially on some of the temperate plants like Darlingtonia.
[*] A pretty varied selection, especially of Nepenthes.
[*] The packaging is actually quite decent - my Nepenthes came in a large box (marked "Perishable, this end up" - not that that actually does anything - but it's the thought that counts) and were well-cushioned.
[*] The size is definitely as-described. "Small" is small. Considering the lower prices of plants you can get I don't think it's unfair at all, and it could even be good if you enjoy being present for more of your plant's growing process.
[*] The website is certainly vintage - but you get used to it after long enough.
[*] The heat pack in my order was nowhere to be found, and the plants were quite cold to the touch. If it were warmer out or I were buying temperate plants, I wouldn't mind - but not including a heat pack in a Nepenthes order during winter (and when the temperatures here are in the 10s and 20s) left a sour taste in my mouth. Thankfully none of the Nepenthes appear to have lasting damage - perks of buying HL hybrids I guess.
[*] The customer service. I tried using the site's email form to ask about the missing heat pack - but the form on the website doesn't even work. I tried emailing the listed customer service email address, but got an "email address does not exist" return message. I've heard the best way to contact Cook's is through Facebook, but I didn't want to make a Facebook account just to ask for a $4 heat pack refund. Thank goodness I didn't need to claim cold damage on any plants.
Overall I probably would order from Cook's Carnivorous Plants again, just maybe not for tropicals during the winter. I appreciate how they offer good plants at good prices (especially some of the harder to find ones), but I don't like the feeling of gambling over whether they'll reach me okay.