I just got one 2nd hand (6 months old) but I've not set it up yet.
1.Yes, it seems to be very well built.
2.Mine came with an internal fluval 4 +, since the original filter had already broken. So the filter that comes with it must be useless.
3.Yes, it looks very nice and is sturdy with nice clear think glass. If i was allowed another thank i would defiantly get another juwel if i managed to find another one for the same price (mine was £175).
4. You do need to cut holes in the lid for the pipes (very easy to do). I'm going to be using a fluval 305 with mine when the filter arrives this week.
The only thing I dislike about it is the lighting, not nearly enough for growing any plants other than possibly java fern and very easy crypts.
I am going to be adding a t5 36 watt compact to the back panel of the hood to double the lighting, which will be extremely easy to fit on.
Other than that the only thing to note is that you cant turn on the two tubes in the separately without buying an add-on from juwel, this doesn't bother me though because i have no need to turn them on separately.
Oh and also, i you want to grow plants in it, I recommend buying 2 juwel 18w reflectors - which are very good value for money compared to other reflector brands. I plan on getting these too.
Oh and as newtankgirl says, if you were going to be paying around £300 for the juwel tank, you should defiantly get the fluval 190 instead - it comes with good lighting and a very good external filter (fluval 205). Dunno about the actual quality of the tank though, but it does look nicer from a design point of view.
Look here.