pro: the parts are complete, they don't have plastic bits or mishappened parts. the quality is very good.
Con: the instruction could show exploded diagrams and have better interim parts sssembly instructs, as actual engine assembly plans have. the parts lists are good, but interpreting the final build of components is difficult. any builder should spend a considerable amount of time examining the component description diagrams, as they are difficult to read and interpret. I am halfway through this build. It has been a challenge. I am an accomplished motorcycle mechanic, and shop manuals are easier to understand for component assembly.
the cam chain was too slack, and has no tensioner applied to the assembly. I shorted the chain by 1 link and got it to work, with crank timing.
I want to thank enginediy for the Raven bird, which had very good instructions. please apply those type assembly instructions to your block engines, they will be winners. thanks for a challenging puzzle.

Directions are extremely vague and some steps out of order. No exploded view to ensure proper assembly. Has a scale saying 1:1 which they shrunk down to save money on printing so you have to guess the right part. All parts put into same bag instead of by subassembly. Have to use other pieces not in set to get push rods to work properly and not fall out. The tolerances are horrible. Had to use a mallet to drive numerous pieces together. Other ones so loose they don't do what they need to. Had several damaged pieces that I replaced with various leftovers from other sets. Overall aesthetic looks great. Fit and finish not so much.

Have not put it together yet. Package came with no issues. Looking at the box it came in can't wait to put it together. Has a Harley fan this is going to pretty cool setting near my bike.

Order and delivery was fast and smooth.

I enjoyed working on this project quite a bit. The directions are more challenging to follow/less detailed than typical "LEGO" brand but if you've built other block creations before, you can probably figure this one out. I did notice towards the end the directions became even more vague and you had to look ahead towards the next step (or two) to understand what exactly you were supposed to do for the step you were currently working on.

First major difference from LEGO is that the very first instruction is to open all bags. You will need pieces from various different bags throughout the entire build so unfortunately (or fortunately if you like the challenge of finding pieces) you can't use "Bag 1 for steps 1-30, Bag 2 for steps 31-60, etc.). I used Tupperware to keep the parts somewhat sorted and quickly caught on to where I should expect to find a particular component.

Most of the 'x' sticks that need to go through the gears and wheels are VERY tight. I ended up bending a few of the sticks trying to force them through.

There were other areas where the fitment was so loose that I ended up using super glue to ensure the pieces would stay together.

Spark plug assembly was arguably the most challenging piece of the puzzle because the components simply would not fit together. I wound up drilling out some of the small light grey connectors to allow them to slide down the white cylinders.

Also, I was unable to get the pushrods to connect (they didn't seem long enough) so when I first cranked up the motor the rods moved a few other components out of the way and ultimately ended up falling off. I do not currently have them connected which is a bummer.

Overall, happy with the purchase but wish the fitment was a little more precise (I can get over the directions criticism).