I didn't buy mine from Mighty Ape but I definitely believe that it's worth saving more and not buying the mini 8. Even with the mini 25 out now, I think the mini 90 is still the best option.
The mini 90 has all the features of the previous instax mini models and a few more. A rechargeable lithium battery; it's the same as the batteries used in the Fujifilm compact cameras. If you still have yours, I'd suggest keeping the charger for this camera. The camera is fairly intuitive to use (unless you've never used a digital camera before). Its standout features are its Bulb Exposure and Double Exposure modes. These are my favorite features of this camera which allow for an infinite amount of creative ideas. It also has a built-in macro mode; the other mini models have a macro mode but require attachable macro lens (usually provided with the camera).
It brings back memories of the Polaroid instant cameras from the 90s. However, now that Polaroid is by far more expensive these days and hard to get, this a decent alternative. That's not to say that the instax cameras are cheap to use. I would suggest buying the film when on sale and in the bigger bulk options (50s or 100s). The range of themed film cartridges are hard to find at a good price here in NZ (I suggest waiting for the Party Packs to go on sale) and the accessories are limited, even at the NZ Instax specialist (instaxshop.co.nz).
There is a bit of a learning curve for this camera which adds to the expense. There are quite a few blogs that offer insider tips so you don't waste as much film during experimentation. It's also a good idea to buy this camera on sale since film is going to be a continuous expense. If you're a parent buying for a teen or child, I'd suggest getting the cheaper models – mini 7, mini 8 or mini 25. However, this mini model looks the least toy-ish which is a big plus for adults.