She was OP before. Now she's even more OP, and I'm lovin' it.
Ricochet is now a 1-point wonder early on, allowing you to max BB right away without losing the powerful harass from Ricochet (used to need 3+ points in Ricochet to harass properly). I max it second now, instead of taking 3 in it immediately.
On the Hunt is an even more powerful team-wide movespeed buff now that it affects anyone that gets into its range. Combined with her passive it's pretty ****ed hard to escape from Sivir and her team.
While she can't have 2.5 AS with only a PD and Berserker's anymore, new Ricochet lets her attack nearly as fast without any AS items at all. It's not easy to use it this way, though, which will set the good Sivir players apart.
She's still as tanky as ever and is arguably even stronger now in a Fratma's/Wit's End build thanks to Ricochet's bonus damage. Now, though, she has the option of building glass-cannon and still wrecking faces. My most successful match today was with a Sanguine/Entropy/Atma's/PD build, though I also had success against a Malzahar in bottom lane with a Sanguine/Wit's End/QSS/Entropy build.
Overall I'm loving the new Sivir.