I saw the new show last night. I really enjoyed it, but I have to admit that I liked the old one better. The new show will appeal to people across age ranges. There is much more contemporary music. I certainly don't blame them for modernizing the show, but I am in my mid 50s and love the classic Motown music and there was less of that.
I was able to get a ticket at Tix4Tonight. Of course, it was a Tuesday night in the middle of May, so it you are going during a peak time, it maybe different.
The theater is small. I bought the middle tier seats and wasclose enough to see and hear everything. The only advantage to buying the top tier sears is that you will get out of the theater a little more quickly.