Global Pen Friends has a few things going for it. The search function is easy to use, and it's relatively easy to find people from the countries you're interested in and who are in the general age range you're hoping for. Compare this to Interpals, a site that I've previously said (and continue to think) is the best site like this, where the search function can be haphazard at times.
The obvious downside to this site is that registration can be a little more time consuming than it is for other sites like this. Unlike with other sites where you can fill out your profile at your own pace and as you see fit, this site requires that you fill out something for just about every part of your profile straight away, and with a minimum number of characters filled.
That might be fine for someone who naturally has a lot to say about themselves, but it's not so great for people who might prefer to talk about themselves with other people as opposed to writing about themselves on a public profile. It doesn't help that the minimum number of characters for the "What you're looking for" field is 90. The statement, "I'm looking for penfriends from the United States of America" takes sixty characters, which I personally think would be fine as a reason for that field when you're first signing up. You're almost forced to follow it up with some low level joke like, "Oh, and for someone to scientifically prove that Tonight Alive isn't the best pop punk band ever created."
Once you've filled out the profile, it can take at least two hours, and they say profiles are usually registered within ten hours. Maybe they've had huge issues with spammers in the past that I don't know about, but this is still an incredibly slow sign up speed. With other sites like this such as Interpals, Students of the World, and Pen Pal World, the registration speed is faster--almost instant, in fact; you just need to click the link they email you and it's fine.
The only way to get around this is... to pay a premium fee. And that tends to be one of the common issues with sites like this: they'll do a couple of things really well, but then they'll follow it up with a thing that's either weirdly limited, or they'll want you to pay them money to get the additional features which are more or less standard in other similar sites.
While I understand the logic behind doing stuff like this, I don't think it's really a viable thing when you have sites like Interpals and, for school kids, Students of the World which offer every feature they have for a premium account. Surely a better solution would be to have certain aesthetic things you can put on your profile if you pay a donation or something, but otherwise have it as is.
The other big downside to this site is that it assumes you'll only be interested in a single culture. While they'll try to hide this by asking you to pick a continent rather than a country, this is still implicitly the case. What if you're interested in both German culture and Indian culture, for example? Well, the site assumes that's not going to be the case and doesn't seem to allow for it.
While the search function is great, I think it suffers from a few glaring issues in the registration process. Surely there's been a number of people who've been driven from the site just because they feel it takes a little bit too long for their liking.