A bit late for the discussion, but since I found the thread...
In this moment, I'm forced to use Legacy mode, unlike before the current year, when I was using the Ultimate client for all the maps (except for the 500p one, which is unplayable with that client). Now, with my current PC (which it's relatively new), Ultimate client is hopelessly unplayable in all the maps: it has lags and crashes every moment, even with the Low Graphics option. Only it's possible to play that client in the mobile APP.
If I was using Ultimate client, but now I must use Legacy because whatever change made to Ultimate that became it unplayable, that says a lot about why do the community takes any attempt against Legacy as a personal daring. This remember me the paradox of the books, which are both the most backward and the most advanced technology in the current time. Likewise, I agree with Slyx when he says Legacy client is a relic from the past, but the issue here is: Legacy is currently, at the same time, technologically superior when compared with Ultimate.
No way! I just came back and everyday while I play I say: the game is so beautiful now!
Note: I started to play in 2009.