Just like in any sorority, you're going to find reasonably diverse girls in theta. They have a reputation for being somewhat edgy, somewhat heavier partiers/drinkers/drug users than the other sororities. Typically associate a fair amount with Owls, Castle, and some of the classically "top tier" frats. Known for their black and gold accessorizing and more difficult pledging process (compared to some others). I know some really sweet Thetas and some thetas whom I dislike. Each pledge class is about 50 girls. You'll get some variety, although they tend to be wealthier, more jewish, and from the LA, Miami, or NYC area. Also reasonably international.
Theta is reasonably exclusive. But they had a lower yield this year. As picked by the freshmen girls actually choosing their sororities (during pref round, when you make your final choice), I believe the rankings were:
3. Alpha Phi
but traditionally, rankings are something like
1. Tridelt, Theta, AXO
2. APhi, SDT, ChiO
3. SK, ZTA
Though recent buzz has been that TriDelt this year was leagues above everyone else, Theta wasn't as amazing, SK is better, and ChiO is worse.
Also, funny thing about Theta and cocaine- I had to go to Student Health Services for a cold, and I was chatting with one of the doctors who went to penn undergrad, and he said that he never actually believed the Theta cocaine rumors until he started having to treat a bunch of them for symptoms of drug use when he started practicing at Penn. So interesting perspective on that. At the same time, it's not like you have to do coke. Do what you want.
And so you know, rush is in the spring, you have plenty of time to decide, and it's a lot about what feels right at the time.