Season 3 Elise main. I've played her in every single role (Yes, I've tried AD Elise before), so I'm aware of the pros and cons of each role for her.
If you want to play Elise mid, go for it. Just do so knowing why it isn't a thing. Lane Elise isn't that great mostly because of the nature of her kit. Rather than being a great mage or a great assassin, she's a lack luster both. In Mage form, your Q spamming is only strong when they're high hp and mana costs really suck early on. In Assassin form, your Q damage is only strong when they're low and people rarely stick around for your W to be useful (granted the E steroid kind of helps here). This lack of consistency, along with your ult cd, are pretty easy to abuse for other laners. Later on, you're really reliant on your E to secure combos against squishies which was nerfed and is kinda easy to side step. No immediate burst damage. No survivibility in team fights because of restricted mobility.
That being said, it's not completely terrible. Point n click damage that's hard to build against because of how Elise builds, nice ranged stun, W provides a LOT of surprise aoe dmg in team fights that no one expects. Good mobility in jungle fights thanks to E. Also good for positioning or getting around front liners. Full combo rotation will pretty much guarantee a kill against low-mid hp targets (or full hp squishies). A skill that's lets you dodge point n click anything or skill shots in general (E) is always nice too.
Keep a little past your side bushes warded and play smart. People that know the game shouldn't give you too much heat, especially if you do well/decent in lane. People that do give you heat don't really matter, just mute and keep playing if mid Elise is what you like to do and it works for you.
PS: Never build the AP jungle item on Elise. Tank/Assassin is the way to go. Rush your two magic pen items if you're ahead or on par. Haunting Guise/Sorc boots (save liandry's finish for late game). Rush cinderhulk if behind. Cinderhulk->Liandry's->Sorc Boots-> Frozen heart (situational, but strong) -> Locket or SV or Banshees-> Randuins (if didnt go FH second) -> Zhonyas or another defensive item if a pretty good build (order changes with enemy priority).
