Hebrew and Arabic are both RTL, and I think the RTL alignment sucks. If it wasn't so hard to type in Arabic text, I would've edited some wikis in Arabic and translate some pages I create to this language. Perhaps, I could even go as far as being a Helper, but nah, the alignment sucks. Trust me, I tried translating a couple of help pages in Arabic, but it was very difficult, between all the complicated text selection and such.
Yes I guess the editor support for RTL isn't great. Though my only experience is from translating stuff on Dev wiki to hebrew, which is harder because it's hebrew and english mixed. I really should do it on Notepad and just paste the result.
However I'm asking what you think about the appearance of the site, not about the editor. This should be just a matter of using the right CSS.
In my opinion there are somethings that should be flipped on RTL wikis regardless of the user language. Plus when I use ?uselang=he it flips almost everything and makes it even worse.