As you probably saw on boards.ie they are far from 'zero-emissions' and in terms of pure economics there are better options around.
Looks are a personal thing but it wouldn't be my cup of tea, I suppose it makes a 'statement' about your intentions though.
I haven't driven the Prius auto but in general i find modern automatics far superior to drive than manuals. Take it for a proper test drive (a couple of hours) or preferably see if they'll let you have it for a day or so. You may be surprised how easy good autos are to drive.