I moved about 6 months ago, and when I came over Vistara was still under the management of Mark Taylor (which was a huge reason why I loved it so much, my last apartment was Mark Taylor and it was great). But a few months after I moved in, Olympus took over and everything went downhill.
I get it that changes like this are hard, and wasn't expecting everything to go perfectly by any means. But what was so disappointing was how unprofessional the new staff is. Things still haven't gotten better and its been 6 or 7 months. They will sneak wrong charges into your account without telling you, so you have to be REALLY careful or you'll get ripped off. I've also been in the office while they've been bad-talking residents. That was a huge turn-off. They are known to lose packages and don't have you sign them out (so really anyone could go pick up any package, which is a huge concern).
BUT two stars because the facilities are really nice (when they're working, the pool and hot tub heaters were down for a long time). But the rooms themselves are very nice. So as long as you don't need to be in any sort of contact with the leasing office, you should be fine. Just be very careful!