I did this for a little while, for mathematics lectures. It's faster than typing them in LaTeX, and very shortly you won't have trouble remembering the ctrl/alt/esc commands (which you should definitely learn). For the most part it's faster than writing. Two pieces of advice:
1) Audio record the lecture (it's polite to clear this with the lecturer beforehand). You can use your computer to do it, and you already have it out. If there's something spoken that you can't get down because you are fiddling with the interface, you can make a note of the time (or evaluate a function that does so) and go back later to complete the notes.
2) Have a plan in place in the event that diagrams are drawn. One option: take a picture of the board (it's polite to clear this with the lecturer beforehand).
I stopped for several reasons:
1) Too many diagrams, and at the time I had no way to take a picture.
2) Typing and writing is less hard on your hands than typing and typing.
3) Writing is more natural to me, even though it is slower. It's easier to concentrate when writing.
4) When the lecturer writes something incomprehensible, it's easy to copy the shape and figure it out later (if it's not a good time to ask).
5) Sometimes it is nice to two sheets of paper out at once.