These Dover score editions are best known for their low prices. For the Beethoven symphonies, these are pretty much just reproductions of the 1865 Litolff edition, which contains numerous mistakes that were corrected in later, better editions. The 9x12 format is good for the full score format, making it easy to view all the orchestral parts at the same time. The note heads are big enough to be clearly legible.
Knowing the deficiency of the source edition, my major complaint is there are no measure numbers so it's a big inconvenience for anyone wishing to study specific points in the score.
BTW, all these are available for free download as PDF on [...]. But for me, having these in a book format beats having to print out page after page of PDF which gets messy.