Only thing to worry about with snris is they are stimulating because of their effect on norepeniphrine, so they're not usually used if anxiety is the main problem. If anxiety is the result of depression, that's a different story. Also, Pristiq is basically Effexor, so if the Effexor gave you problems, you might want to think about taking what is mostly the same thing updated to get more patent protection, kind of like Celexa and Lexapro. Not exactly the same drug, but very similar. Some will have very different reactions to the two meds, but again, you're not in a category usually used if you're just an anxiety sufferer and you've essentially already taken it with apparently bad effects when you took Effexor. On the other hand, only way to know is to try, since this is all trial and error.
Pristiq is my miracle drug. I have had the absolute worst anxiety since I was 2 years old. I started taking Lexapro...but that didnt do anything for me. Then I took Pristiq....and my anxiety went from 100% 24/7 to almost 0...in a matter of 2 weeks. I can honestly say that it has saved my life. I take 50mg which I believe is one of the lowest doses and it worked absolute wonders on me. Everyone is different, but i definitely would encourage you to try it.