I had a Gardena automatic watering system at my last house and,
although it worked OK, it was an absolute pain to set up. They did a
fantastic job of making it look simple on the pack but, when I opened
the box, I was faced with dozens of little plastic bits that all
looked the same. I think it took about six hours to set up and then
even longer 'tinkering' to get all of the drippers working as I
wanted.

I too have an 'urban' garden in my current house, with mostly pots and
hanging baskets. Last summer I bought a Hozelock AquaPod system and
it's brilliant! It took about 10 mins to set up and has automatic
drippers so there was no tinkering involved. The kit came with two
'pods' and a timer, plus I bought another couple of pods to add on.
Each pod has five drippers (from memory) but the pods link together if
you need to add more (my system looked after about 15-20 pots last
year but I'll be adding more soon).

Another good point is that it only took 5 mins to pack away once my
pots had gone over, whereas I had to leave the Gardena system out all
through the winter.

Good luck with whichever system you choose.