We've got an Aqua One 510 (is that the same, or does Ar mean something different?) Assuming it's the same: I'm fairly happy with it. It's the only tank we've got (so far!) so I can't really compare it to anything else... but here are my thoughts FWIW.
Advantages: the filter is fitted into the back of the hood, making it very accessible and easy to clean. Water is sucked up from the tank, through a spray bar over the filter, and then down into the tank - seems to work OK, and doesn't risk leaking. Lights are built into the hood, and there's a slot for the heater. It doesn't take up much space, and you can get a cabinet to fit underneath. The filter is supplied with cartridges containing carbon, but you can swap these for plain white filter pads if you don't need/want the carbon, and most shops (around here anyway) seem to stock the parts. Flap at the front of the hood makes it easy to feed. Looks good - you can get silver or black hood/trim, and the seamless curved front corners are nice.
Disadvantages: It's quite tall for its size, makes it a bit harder to clean gravel and the bottom of the glass. It's acrylic, so can scratch if you're not careful - need to use non-scratch algae cleaning pad or wool, and be careful not to catch any gravel between the pad and the glass. The filter construction is a bit unconventional, as the instructions tell you to set it up so that the water goes first through the white cartridge/pad, then the black sponge, then the ceramic noodles. In our tank, this means that the white pad/cartridge gets very clogged up and needs cleaning at least once a week - but that may be because we've got loads of plants and some very messy platys, so you might not get the same problem. (On the other hand, the black sponge seldom needs cleaning.) Also get lots of bits of plants clogging up the spraybar. When you want to get into the tank, you have to take the whole front part of the hood off, unhooking the cable supplying the lights from the slot at the back with one hand while trying to balance it with the other, wipe off any drips of water, and find somewhere to put it where you won't tread or trip on it while you're working. Lights may not be bright enough if you want heavy planting, and as they're built in, it might be tricky to replace with a different type (though so far they seem quite adequate for our plants).
I think some people have replaced or supplemented the filter with internal/external filters, if they need higher filtration - so far it's been fine for us.
On balance, I'm quite pleased with it. The accessibility of the filter is a big plus. My main gripe is having to take the hood off to do a water change and clean, but it's not a big deal. A couple of my fish are jumpers, so I've put a wodge of filter wool around the top of the heater where it hangs down into the tank so they can't get through. We didn't have space for a larger tank, but I would say, if you can fit in a bigger one then do.
Hope this helps - let me know if there's anything else you'd like to know?