Well I'm a big hydro fan so here is my list:


PROS:
1. Plants do very well in hydro if taken care of correctly
2. Plants will grow faster in hydro than in soil
3. much more control over environment
4. better yield per plant (my opinion only)
5. less diseases and pest problems (generally...again imo)
6. more stealth than outdoors
7. easier to pinpoint and fix problems with plants
8. You can grow your plants anytime of the year....not just summer


CONS:

1. the expense....and besides just getting started equipmentwise the environmental control so highly prized is expensive..the nutrients and additives as well as lighting, temp control blah blah
2. Often more height and space concerns than outdoors
3. more daily work required to keep plants healthy and happy.....you can't go off and leave hydro for a few days....certain things must be checked at LEAST daily.
4. when there is a problem your plants can crash and burn very quick
5. Unless you have tons of indoor space it's much easier to grow lots of plants outdoors rather than a few plants at a time in hydro (assuming you are going for quantity)