Glad she arrived. I'd email the seller first and thank them for the pony being as described and safely delivered and communicate your complaints.
Depending on their response to that, I would leave neutral or good feedback with a note of the delays. Good feedback would be for good customer service, which goes a long way with me. If the seller acknowledged and tried to address it. Neutral if the seller isn't responsive or doesn't care. Bad if it blows up in your face and the seller goes off the deep end, which I doubt will happen.