I built the HF trailer last Fall. The electrical stuff sucks - do yourself a favor and run a better ground to each of the lights. The instructions imply you should ground through the chassis, but that doesn't really work due to the paint. Works OK in some applications, but this is not one of those.
Hubs on mine came greased, too, but grease them again anyway. Buy a spare tire, and make sure you have a jack that'll lift the trailer should you actually need to change a tire.
On the square hole 'locking' bolts which secure the folding portion of the trailer... Put the nut side out to facilitate ease of removal.
Learn how to fold it - there are techniques on youtube that show you tips and tricks with a ratchet strap to lift the deck and counterweight it, making it a little easier.
Be careful on the deck thickness; too thick, and it won't fold properly. You may also need to cut the corners of the deck to ensure folding, due to bolt bolt clearance. (Depends how high your bolt head sticks out off the deck.) If you're mounting stands to the trailer, it probably won't fold up all the way anyway, but I just learn my stands attached and fold up part ways, with a ratchet strap to hold things together at the top. Much faster than taking them on and off every time.
I think I had ~$400 in mine by the time all was said and done, including title and registration here in NC. It's a pretty good value. Mine unfortunately has a seriously sticky receiver, and it doesn't cleanly push the fork down to release the hitch ball every time I try to remove it from the Volvo. Have to pry a little bit, and pull. I suspect it was somewhat crappy from the factory. Might replace it, or try to bend it back one of these days.. Currently too busy to be bothered by it that much, however.
Lastly, it can definitely help to put extensions up front for tie downs. I ran a short section of angle iron, which protrudes about 12" off the front of the trailer. Kinda like this.
If you're transporting one bike, you probably don't need them... But if you're hauling two bikes, you'll absolutely want them.
PS: If you don't reinforce the fenders, they'll literally crack the trailer frame. They're way too heavy, and the drag/turbulence will vibrate them until the trailer cracks. Find some way to secure them - google this.