So, do you think we'd be wasting our money paying for things we don't need? Or is there something better? Are games what it's mainly intended for?
Not necessarily. It really depends on the kid and what you want to be able to do with a tablet. I just know for us, we didn't really end up making use of the extra features like the chore chart and coins and DD wanted to use the apps and play the games that her friends had on their ipads and such, not so much the ones that Nabi offers. I do like that I have to put in a password and specifically make apps accessible, but that's the only feature I really make use of and other tablets can be set up to do that as well. I also think it just looks more baby-ish and she's not going to want to be using it in another year or so even though it's perfectly functional.
I would also look at the Kindle Fire and Nook HD if you want something book/education centric.
Two of my older kids have Kindle Fires and I find I can monitor them just as well since they're connected to my Amazon account. I don't have to physically put in a password every time they get an app, but I get an email so I'm aware. I also have anything that needs to be purchased with money PIN protected. They also offer Freetime parental controls which can be used with or without the monthly subscription and I was able to set instant video parental controls for each device. Google apps can be side loaded. DH has a Nook HD. Nook allows multiple profiles so you can restrict things for kids with it and it also has Google Play Access.
Both the Kindle Fire and Nook are about $50 cheaper than the Nabi although you'll also need to get a case. We've been pleased with $10-15 Flintie covers from Amazon, but if you feel like you need something more robust, it could be more. I do think though with these, while it's a little more effort to set up the controls, you won't have any possible issues with it being outgrown. They are all 3 great, functional tablets though!