Ehh, it looks kinda... lame.
I mean, I've seen better. Much better
Effort usually shows through so a custom built project that probably took hundreds of man hours should
be better than a mass produced costume. The linked video shows a costume that's fine for display purposes but you can't do a lot in it. I've seen other videos of the guy plodding around and scaring people, hehe.
I found this home made costume
that I think is pretty good. At least the wearer is more mobile. Unfortunately, due to average human proportions, most people who wear such a costume will look like Mighty Muggs Optimus Prime. I think with some tweaking, slim down the costume in areas like the boots, it could look less chunky. Get someone particularly tall and you'd have a pretty good Optimus Prime.