These asvab practice on military.com are really good. And yes they are very similar question as to the real one. My first ASVAB practice test that my USAREC gave me I scored a 33. I practiced on the military.com website for a week and re-took the practice test and received a 47. On the real test I scored a 57!
I would encourage everybody joining the military to practice.
PS: all these results after one week of study on the military.com ASVAB practice test.