I'm only 12, but I've been playing neopets nearly since it came out, so I started playing it when I was about 5 or 6. Neopets is a great site and teaches kids to care for pets while also teaching them money smarts (the virtual money can be spent wisely so you can become rich with great pets or you can spend it on random junk and become broke). Although you can buy real-life items from the site, you need a credit card and few little kids have their parent's credit card number memorized, so I really isn't a huge issue. Although some of the neopets games have gambling, the gambling ones like the slot machines and keno can only be played if your account says your age is over 18 (and mine does; my sister created it a while back and then gave it to me). I don't know if there is an age restriction on the stock market, but I sure didn't understand it when I was younger, so I pretty much kept away from buying and selling stocks. I doubt many little kids would be interested in it anyways.
I say this website has some educational purposes. When I was in third grade, my class would play maths nightmare on the smartboard (before it became updated and hard to click on the bubbles) to study for our mad-minutes (1 minute to complete 100 basic math problems). In school last year (5th grade), my applied tech teacher suggested the game typing terror on there to help with our typing before our test. My mom and I also enjoy playing the word games together like word pyramid, spell or starve, and word poker (the last two are fine for kids, mind you).
Neopets, clothing wise, is FINE for children; the worst item they have is 'My sister's frilly skirt', given out by the advent calendar in I believe y8 or so. I've heard countless arguments over that item, but I feel it's fine as long as you don't have a bad mind.
Chatting is fairly safe; there are a lot fewer spammers than there use to be, mainly because viacom has decided to start issueing IP bans more often. Also, if you try to curse or post bad things, the neopets filter now automatically blocks the post and doesn't let it go through. Although you can post off-site links, the link is taken down a few seconds afterward and you get a warning sent to you from TNT. Yes, you can talk to anyone from anywhere in the world, but basically any chat thing you can do that. TNT has moderaters swarming the boards 24/7.
Although some things on neopets are hard to figure out, most people start to understand them not long after starting. There are great, kid-friendly guides all over the internet, too (on-site and off) and it's fun if you have friends that play too so you can find out stuff together. Just the other day, I showed one of my best friends who's been playing neopets for a few months how to earn 30k from just playing a few easy games and also how to use the shop wizard to find low prices on food.
I think this game is good for anyone, whether they are 6 or 60. I've found many adults who play neopets (they have their own guilds that they create and create their own boards to find other adults usually) and I know a few little kids in real-life that play neopets. I would suggest this game to anyone who wants a break from real-life and a chance to care for a pet and play games.