Yes, he ultimate does provide a heal (actually functions as a heal, not a shield as many people think), so that champion does get to keep that health. A champion at or near full health won't get to keep the surplus, however (that does become a shield), but I find that her ultimate is used best after that friendly champion has taken a bit of damage (which usually happens in the process of getting in the middle of the opposing team), and that usually maximizes utility anyway.
Alternatively, it's still pretty handy for nothing but making clutch epic saves, by either casting on a friendly carry who is getting focused down,or alternatively even self-casting just for the short duration knock-up which is followed by a slow.

Doesnt her ult heals aswell?

Nice build and guide, thats pretty much exatly how i build her but it all depends on the game. sometimes i make an entire team of yordles and these tiny tearors have yet to lose >:3 my favorite combo is Wild Growth on Kennen when he uses Slicing Maelstrom too initiate a team fight.

maybe you could add some pictures of Lulu and her skins to break up the text a little more. other than that its excilent! +1