That's what my 7th grader did this year. We've never really done a formal science before so I thought the science in ECC was fine. I'm very relaxed with science until 8th grade when we plan to do Apologia General. I've just had my dc read a couple of the Elementary Apologia books and all the Christian Liberty Press Science Readers. My dd LOVED the Properties of Ecosystems book from ECC, and this is a girl who's never liked science anyway.
Now I will add that we fizzled out on ECC a little more than halfway through it this year. However, it wasn't the program's fault. I just had a lot of health and learning disability issues going on with my 8yo, so couldn't spend the time doing ECC with my older two. I tried to have them do it independently, which worked for a few weeks, but it didn't seem like they were getting as much out of the program that way. We've since dropped it, except to play the geography games now and then.
HTH!