Lulu isn't all that great because you used to be able to max Q in lane and be super annoying because her poke damage and range is good, and rank your shield 2nd. Your shield would scale on items and it lasted a long time so it was okay to max it second.
Now though it feels like if you don't max your shield it's really weak, but if you max your shield, then you have really little presence in lane as you can't really trade with Q. If your lane opponents know how to play against you, you just get screwed.
Soraka is a much better pick atm because healers were left mostly untouched. They lost 9% heal and shield power at full build I think, but they weren't gutted case by case like shielded were. Soraka's silence is often better than Lulu's polymorph, Soraka's resources are far more manageable than Lulu's because Soraka's Q with one point in is very useful. Soraka's R heals for more health than Lulu, Soraka synergises well with mikaels. Her heal cooldown is really low compared to Lulu's shield... There's a lot that makes Soraka a far superior pick to Lulu atm.
Lulu is also a champion that synergises with late game hyper carries, and those champions need far more than Lulu's ult and polymorph to keep them alive in a fight nowadays. If I lane with a late game hyper carry I'd rather play buff bot Rakan
because I know my RW, Q heal and E shields will buy them far more time to deal damage than Lulu could with her abilities, the bonus damage from zekes with abyssal amplification is nice.
It's not impossible to play her but if you don't get a lead early by the enemy players being bad then it's probably going to be a hard game.
Long post but w/e. This is why I don't play Lulu