Some plumbing codes prohibit vents placed on the exterior like that. In non-freezing climates, the pictured installation should function properly-- and that is perhaps the most important consideration.The horizontal line is to get the vent above the flood rim of the lavatory. Having the line at 45 degrees from the taller vertical vent stack instead of horizontal should comply with the code and would make the exterior piping a little easier to conceal since the piping would then be farther from the brick window sill.

Building a shallow bump-out (vinyl siding?) to cover the pipes is one option. Check with an HVAC contractor to see how they conceal exterior refrigerant lines.

Yep, it either needs to go inside or outside.

That said, I would talk to the contractor about getting the pipe as close to the wall as possible. He left a lot of space between the pipe and the wall.

Then I would frame in that wall with 2x6 or steel studs and cover it with hardi plank or if you are going to stucco the rest of the house, do the same after furring it out.

Thanks for the suggestions. I mentioned the 45 degree pipe instead of the 90 degree one before I left for work and when I came home he had installed the wooden blocks behind the pipes to secure it more firmly to the house and made it look even worse! Will definitely present both of the options offered on Monday. Thanks!!!

Remember the Golden Rule-- "He who has the gold makes the rules." Until and unless the workman gets his pay, you have a great deal of leverage. After he gets paid, you have no leverage. When he gets the money, you are stuck with the situation as it exists at that moment.
So do you want to be the Stuckee or the Stuckor?