She's very fun but not particularly impressive. She has two gap closers and good sustained damage. Otherwise she doesn't bring much to a team. She has low utility, she's a mediocre jungler, and a mediocre top lane. She's not a bad champion by any means, she just doesn't really shine in any area.
Originally Posted by Onimus Terlain
Give it time.
She's going through the early stages of release that every champion goes through.
They are created.
Played for a week or two.
Then players fall off.
Then they erupt once they are figured out.
It happened with Riven, Yorick (granted a buff came with his surge), Kha'zix, Rengar (a little faster than others), Lee Sin, Hecarim, Jayce, Rumble, Shyvana, Skarner, Viktor and Wukong.
Now, each champion listed "erupted" at a different rate. But it's the natural cycle of champions.
Vi will be given the time of day once the pros figure out how to best utilize her, then the community will follow suit.
Many of those champions received buffs before they became popular. Specifically Riven, Yorick, Rengar, Lee Sin, Hecarim, Skarner, Rumble (was OP on release, after he was balanced he disappeared, had his flamethrower 'fixed which ended up being an unintentional buff and he exploded again), Viktor, and Wukong. That just leaves Jayce, Kha'zixs, and Shyvanna and of those three, though he flew under the radar for a while, Jayce was OP on release.
Vi is a very simple champion to play. It's not like people are unaware of her potential. She's also quite fun. She isn't being played anyway. There's a reason she's getting a buff.