first time you call the menu it takes few seconds until it shows.
These are startup delays (without them, it would not start on 32GB cards or so).
the menu flickers.
My fix for menu flicker was causing the camera to freeze, so I've left it flicker as much as it likes. The solution is to find the redraw event (maybe?) and block it from menu_handler by returning 0 instead of 1. Original Trammell's code blocked lots of events (and didn't have flicker); my code lets almost all of them to go through the camera (and you can also change shutter/aperture or start recording while ML menu is active).
when i try setting the ISO my camera goes into some kind of loop where it keeps setting the ISO.
Early 550D builds had infinite loop (it keeps trying different value until one is accepted). Recent builds have a limit (max 10 tries).
zebras broken. you will see the red zebra all the time in LV (unless you are focusing)...haven't started looking into this one
Check if VRAM buffer addresses are OK. See the 60D thread and the VRAM/550D & VRAM/60D wiki pages.
HDR: I understand how the hdr shooting code works but i haven't figure out what triggers it. if i half press the shutter button the feature gets turned off...still working on understanding the trigger part of the code.
It's triggered by intervalometer, remote shots, or after a picture is taken. In the last case, first exposure will be 0EV, then -3,-2,-1,1,2,3 (for example), and will also trigger a 2-second self timer to avoid shake. In other cases, 0 exposure is in the middle.
intervalomenter seems to be working fine. sometimes it takes few seconds until it gets triggered, after which is working just fine.
Very latest 550D build makes a half-shutter press every second to avoid camera going to deep sleep (when it would not wake up from msleep's).