Andy, we've got two Juwel tanks, a Trigon 190 and a Vision 260. We've been pleased with both. The quality of the tanks and cabinets is very good. The cabinets come flat packed and are very heavy, but we found that they went together much more precisely than most flat packed stuff.
There is an internal filter powered by a small pump. You can see the filter in this photo:
The filter is virtually silent, unless you fit the optional venturi kit, in which case you will get some noise from the bubbles. The filtration is perfectly adequate for the size of tank, although I prefer to over-filter and have fitted both tanks with additional external power filters. I think the oxygenation is OK as standard, however we've fitted the venturi kit to the trigon and the Vision has an external air pump running a bubble curtain along the back of the tank. The bubble curtain is more about avoiding dead spots in the rocks than oxygenation.
The lighting is variable. To be honest, for plants our Trigon's standard setup was completely inadequate. We've added another tube. The Vision has two big T5 tubes and is fine. I think all Juwel tanks now come with T5 tubes, so make sure you don't end up with old stock. I'm tempted to upgrade our tank, you can buy the new T5 light bar separately for about 50 quid. The tank has been running for several years now and I'd quite like to redo it from scratch. I'm tempted to upgrade the lighting, fit a CO2 kit and run it as a proper planted aquarium.
The filter at the back of the Trigon: