Well, after spending ~2 hours to get 55 thieving and contemplating cutting my wrists, I decided to write up a quick report of my progress.
1-10 : Fine, pick pocket humans until level 10. No problem there.
10-40 (Farmer) -60 exp per click: Rough, but I got a lot of seeds which was nice. Hopefully useful for farming, however probably not (yet) at least.
40-50 (Guards at yanille) -130 exp per click: Also rough, fighting trying to thieve while other players are using the guards to train combat. Also constantly moving. Kind of slow, also annoying. Not a bad tactic, having players do something besides stand there and click the same spot over and over.
NOT REWARDING.
50-55 (Silver stall @ardy) -1k exp per click every approx 30 seconds...works out to be no different than clicking the guards at yanille experience wise (No faster). Having the knights attack you is a nice addition. +1
I originally got excited once I hit level 55, woohoo yanille chest time! Jokes on me, I click the chest "nothing interesting happens".
TLDR: (basically thieving is like at 50% working)
-Boost experience for completing tasks farther progressed into the skill
-Fix/add yanille chest (legends too I presume)
MAKE THEM USEFULL! ALSO REWARDING
-Make thieving have a "point".... make it more useful. Example : instead of getting silver ore from the iron stall, make it give a variety of bars or something
-Add more content... Example more stalls, or a "master farmer".
-Also fix guide