I own a TIG welder and have done lots of welding with mild and alloy steel (mostly 300 series stainless).
TIG welding is like learning to ride a bike. It's difficult at first because various parts of your body have to work in concert, but once you get the hang of it you can do really great work. I've not done much overhead welding yet though, that's where the wages are earned.
I've completed a certification in TIG, MIG and Stick welding and metal fabrication.
Welding overhead is considered more difficult because gravity is making the molten metal run away from the joint. Less metal in the join means less strength. Too much metal means you have wasted welding rod AND possibly put more heat into the weld than needed which weakens it as well.
For pipe welding if you can imagine a horizontal join of 2 round pipes, coming around the underside is where you will be doing an overhead weld.
TIG welding is like learning to ride a bike. It's difficult at first because various parts of your body have to work in concert, but once you get the hang of it you can do really great work. I've not done much overhead welding yet though, that's where the wages are earned.