From what I gather (and I’m no Freeze expert) it’s the paint job, suit inaccuracies and being underscaled.
Collectors are pinning their hopes on another 3rd party (Mars?) or licensed (JazzInc?) Freeze which may or may not materialize.
I personally decided to not PO and hold out for a future Freeze. But with the Devito Penguin, I jumped on the Eternal Toys version even though that figure gets a lot of hate too - i accept the flaws but it’s a decent placeholder until the Mars or JazzInc Penguin is ready.
I don’t think you should let the hate detract from your personal enjoyment. Even the best figures on the market get their detractors, can’t please everyone - it’s the nature of this niche but vocal hobby.