I wasn't sure if I report alpha3 bugs here or in the Bug Reports section, so let me know and I'll move it over there.
First, let me say that Alex and the whole ML team are geniuses. I've been playing with ML all day and here are my thoughts:
-- Positive: --
1. LOVE the new gradual exposure setting and the blue/red indicators are really useful to track the transition between exposures. I hope the developers find a way to make it work as smoothly on the other DSLRs (T2i please!)
2. The fine dots setting of focus peaking seems to work the best for me right now, but I can't really tell what the difference is with alpha blend. Extreme sharpness has a lot of potential if it was fine-tuned a bit more in future versions to make it a little more obvious
3. Fast focus box is very fast and responsive.
4. Love the anamorphic stretch settings. This is a feature I requested for my T2i that I hope makes it into release 2.4 (please)!
5. Can't wait for the full release to come out!
-- Bugs that I've encoutered: --
1. Redraw problems when any Canon native UI screen elements are called up (e.g., the * button). Native UI draws over the ML UI and it doesn't come back until a second later.
2. The battery indicator seems to be missing. Maybe it's not a bug, but just hasn't been implemented yet.
3. Focus confirmation in magic zoom isn't working for me. I use green bars, but none of the other settings seem to be working either.
4. When magic zoom is used on any of the anamorphic preview settings, it rescales it to be square pixel.
5. When anamorphic display is turned on, you lose focus peaking.
6. The Dim REC LED doesn't seem to do anything when turned on. It seems equally bright when it is on or off.
7. Focus Peaking > Local Focus seems to only work with Blinking dots. If it's only a feature that's only available for this setting, gray it out when something else is selected.
8. Focus Peaking > Fine details causes significant lag in Liveview. Strong edges and Balanced work pretty well.
9. Not a bug, more of a feature request. The vectorscope takes up too much of the screen as is. Please make a "small" option for the vectorscope like the waveform and put it in one of the top corners, or possibly make the background completely transparent or at least more transparent (maybe like 25%)