I must say I quite like XTA - it's just the least buggy mod I've tried so far and it keeps most of the TA stuff while making some funky improvements.
Some points though:
a) Bug - If I click "area attack" and select somewhere, sometimes I get LUA errors pop up in the console telling me that math.random recieved a number that was too small (or something to that effect).
b) question/suggestion - What does "area attack" actually do? I'd suggest re-writing the comment for it to make it clear what it does.
c) bug? - Many units have "repeat" OR "stop" buttons that shouldn't have them. I.e. Radars.
d) suggestion - The "wait" button is nice and useful, but could it possibly be a "toggle" button. Either change the text from "wait" to "go" when the unit is waiting, or light the button up when it is toggled.
e) suggestion - Aircraft have the funky "land at x% health" option (which is nice!). May I suggest putting this option onto the aircraft plants too, such that the aircraft can inheret the setting from the plant they were made at.
f) question - What's the shortcut for "select all units of the type already selected"? Because ctrl-z doesn't work (what it was in TA), and I've tried a few others which also don't work.
g) question - What's the shortcut to select the Commander? Ctrl-C seems to do funny things with the camera.
Is there a list of XTA shortcuts somewhere?
h) Bug - Playing on 1280*1024 resolution - If I create a unit-group number 0, it appears on the bottom bar (which is a very nice bar btw

i) bug - Building times are shown in minutes if that's how long they'll take (nice feature). But if a building has been abandoned whilst being built and has a red number to show time until it disappears - that number will always be in seconds (i.e. 300 seconds rather than 5 minutes).
j) bug - If I tell a structure to "force attack" - there's a good chance it won't actually do that. I.e. get a heavy laser to attack somewhere that is in range, but it doesn't fire at some places when this order is given, even though they're in range/los etc.
k) bug - The "resurrect" animation icon appears when you mouse-over wreckage that cannot be resurrected (i.e. half-destroyed wreckage that has no shape). Clicking does nothing. You have to manually select "reclaim".
A very nice mod overall though.