I hope it helps you find your Sizemore roots.
The reason I didn't recommend their test is because they don't identify your Y-DNA Haplogroup (the DNA haplogroup of your father's male paternal line) or your mtDNA Haplogroup (the haplogroup of your mother's female maternal line); nor do they have online tools to help you compare your chromosomes with your matches and their chromosomes with each other. This is very important information to know in tracing the correct paternal and maternal lines, because there are so many different lines with the same surname -- each with a different haplogroup identifier -- that are not related to one another.
If I didn't know to which Y-DNA haplogroup my father's line belonged, I might have spent years researching the wrong Powell line, as we also have distant Powell cousins in a completely unrelated Powell line. We think they may be related to us via a female ancestor on my gg-gm Alford's side of the family -- an Alford, Strickland, Felder, Curtis or other -- who married a male Powell from a totally different and unrelated Powell line.
The 23andme.com test is $20 more, but the information you get for that $20 is worth so much more. You get your ethnicity breakdown and about 1,000 cousin/family matches, but even more important, they identify your paternal Y-DNA and maternal mtDNA haplogroups. You also get the chromosome comparison tools, and lots of other great features as well.
Just something to consider for the future. The Ancestry.com test is definitely a good starting point, though. It's the one I started with, too.
--Deborah