I bought this item (in store) recently and thanks to a good friend was able to make a lot of progress in assembling. I had seen the comments and reviews here that indicated that assembly of this Pergola is basically a two person job. I can confirm that is the case and that you will also want to take your time to sort through the pieces and go slowly so you don't have to (hopefully) disassemble and reassemble parts.
Even if you do take your time though poor identification/labeling of the various parts will likely mean you will have to work around issues or wind up do the dis- and reassemble dance. To explain - the parts have stamped identification numbers on the ends. Yay.
What they lack though is good solid indicators of which way parts should be oriented. There are multiple parts, such as the corner posts, that should be oriented with an eye towards "inside" and "outside" so that the posts face each other as they should and more so that the pilot holes that were drilled in the posts are where they are supposed to be. If you miss this orientation you'll wind up having to drill holes in the pieces (posts as an example) because the pre-drilled pilot holes are on the wrong side of the posts.
The pictures that are in the instructions and the written instructions don't at all make clear this issue so you are left not knowing of this until you are much further along and chances that you'll want to deal with the required rearranging of the parts (after you disassemble and reassemble) are not very high.
Similarly, the beams that you assemble for the length across the top area have predrilled pilot holes that are meant to allow you to easily screw (lag bolt) the rafters down. If you didn't know in advance to look for those pilot holes and make sure you orient the beams properly you'll find that you will need to drill new pilot holes and may have a tougher time getting the parts aligned and spaced out as they should be. Myself and my friend were lucky enough to get one side right so we could use the spacing from that side to get things closer to correct but then I was left having to mark what should have been the bottom of the opposing beam with marks where the pilot holes were (which were at that point on the bottom of the beam).
Buyers also need to be aware that this item comes in 10 foot length boxes. That may confuse buyers because the longest length for this Pergola is 14 foot. This is accomplished by having the pieces overlap/butt up against other pieces in strategic spots. (For example, where you see the curved arch supports coming up from the posts to the beams). This is also done for the boards that run across the length of the top. Those come in two parts (some of the other parts come as 3 parts that are joined together) and are joined pretty much in the middle, one angle cut meeting another angle cut. Assembling those pieces can be a little tedious but at least the pieces are smaller and lighter for handling during most of the time you are working with them.
In the end, I'm happy with this item, though will be a bit frustrated with needing to oil/stain and seal it to protect it.