I've got one of those. Technically it's an "Angel Gate" doll head, meant to be "pullip-
like" rather than a flat-out clone. (But honestly who do they think they're fooling? And this reseller certainly finds "clone" to be a selling point!!
)
The plastic quality is very good, not at all brittle. It's heavy and thick enough to take some carving. So for experimentation, I'd recommend it!
As for ye olde legit Pullips, if you're wanting to get into customization I'd recommend haunting the 'bay and ShopaDollic for custom bait to show up. If someone else has already mucked the doll up, you'll be less likely to feel bad if your customization attempts go awry.
All that said, many Pullips are already fantastically wonderful in their default state, and I highly recommend getting one at some point. (tho you may want to swap bodies... and wigs... and indulge in some other light customizations...
or not, it all depends.
)