I'm on my 2nd year of paid for Pro flickr account.
I only really went for the Pro account as it meant you could upload that many more photos. This was an issue because I was in the middle of a project and had just about hit the 200 photo limit of the free account.
I now have 700+ photos on there.
One of benefits of a Pro account is that you can turn on Stats, then you can see how many people are viewing your photos individually, in sets or your entire photostream. Sometimes when I've uploaded what I think is a corker, I check back several times a day to see how many views it's had. You can also see how people are finding your photos, whether it's a link from Facebook, a blog, google or here.
It does help give you an idea of which of your photos are better, though not necessarily why.
Good move though, more exposure the better and there's lots of people on flickr to give you constructive criticism.
