Mild and especially stainless are a beaut to weld with a TIG, no splatter to worry about lots of control, the only issue is take far longer to just tack stuff up and it's much more fussy about cleanliness as the tungsten can get contaminated as well as the work from stuff that would normally just boil off with MIG (fingerprint grease, etc).
Ally is an art though, we've done plenty of ally on the buggy since we started playing with the TIG, but much lower than 2mm can be a pain.