Alright, I've played a few games as the Queen and all I have to say is that she is super ridiculous. People are complaining about Sedna being OP, but I think the Queen has her beaten. My main reason for saying this is her ability to push into enemy territory and capture their portals early. My friend and I won a 2v2 in almost exactly ten minutes by aggressively pushing into their lanes. I'll explain how, and let everyone decide what the best thing to do is. (Note: Regelus can stop it if he's not dumb, but no one else can do much about it... well... maybe Torchie could. 
)
Step 1: Take Bramble and hide in your flower.
Step 2: Buy 3 mana potions, 2 TP Scrolls, 1 Rejuv Potion
Step 3: Blitz the middle flag and cap it. This will give you 66% of a level.
Step 4: Blitz the left side and try to cap the flag there, too. (The one that lets you capture a gold mine when you push forward to further ruin your opposition) This will raise you to level 2, at which point you take compost.
Step 5: Hang out on the flag and try to stop the opposing team from capping it. Try to avoid casting any spells. At levels 3 and 4 take Uproot.
Step 6: Cast uproot whenever you can. If you aren't being harassed then you can attack the towers from outside of their range and speed things up because of Compost.
Step 7: By this point you should be pushing into/have capped the enemy portal flags. This usually happens at around 4 minutes to 8 minutes, depending on what's up in your lane (8 minutes means you're solo against two DGs).
Step 8: The final step. You have two TP scrolls. TP back to base once you run out of mana pots and start upgrading units. Spawn rate, damage, armor, and the units themselves. Buy whatever mana regen you can and at least one more TP scroll and TP somewhere. The somewhere depends on what's going on. You can move to the other lane and knock out all of the towers for your team mates if you want, so that it's easy to get into their portal flags for everyone, or you can TP back to the side you pushed and start taking out the towers in their base (Less Towers of Light makes the others easier to kill, ETC, ETC). You can also knock out the towers in mid and try to cap their unit buffing flag to end the game faster. With catapaults you pretty much rape their base.
That's my guide to playing QoT, and also my thoughts on what happens when people are dumb. It can be countered, but only easily by Regelus. It helps a lot that I can attack and move at the same time... but not being able to target really does blow. :/ Only really makes it useful for running away (which you probably need to do at steps 4 and 5, kite them into the tower, if they follow they die. If they don't follow, chase them back and don't let them cap the flag if you can help it).
To Counter: Regelus can throw mines in the path leading to the portal flags. This blows you up... but Bramble can make that less effective than it should be. You can still run up and Uproot the tower, but you'll lose a lot of life and/or mana to Regelus. That being said, Compost QoT does a lot of damage to Regelus, and you can just sit there attacking him and Brambling yourself instead of the tower... he'll have to leave eventually. That's the point of mass mana pots. You could also get a lot of Rejuv pots if you think they're going to damage you a lot... I kind of got off of the counter topic.
Other Counter: Besides just playing Regelus putting two heros in a lane really slows this strategy down. It's hard to push a tower solo against two even with her imbaness. Problems arise, however, when everyone on a team picks QoT... :/
Other Counter: You can also camp the portal flags. Hit them with the anti-cappers. Stuff like that. It slows the strat down, but it costs money from you, which you aren't spending on pots/upgrading/items, so at your own peril.
Other Counter: Upgrading your buildings. I normally don't bother doing things like that, but if I was against a QoT or two I probably would (if they were pushing like I do). It'll slow you down at least.. the problem is that this happens very quickly. Usually you won't have > rank 1 of Tower Regen before I've blown up one side, but if you get it fast enough it can make QoT have to use more mana potions per tower, which will stall her out pretty quickly.
Anyways... I love Queen of Thorns, to be honest I hope they don't nerf her, I just hope they give the other heros a way to stop her that doesn't totally gimp them. I should also note that your hero killing power after about level 7/8 starts to fall very quickly. You really can't gank anything, but you can kite them around flags a lot, so do that. As heros start to get stuns a well timed attack can take you down pretty quickly. I do like to get Boots of Speed and a Wand of Movement so that I can flee from incoming ganks, so those are things to consider.
Possible Solutions: Increase Tower HP. Granted, you could play with stronger tower settings (all of this is done at the default settings), but since that isn't the default, I'll assume default settings.
Possible Solutions: Reduce Uproot Damage. I don't know about this one. If you upgrade the towers it doesn't do much damage at all, but most people don't want to do that, and it happens so quickly that it may not be meaningful to try anyways.
Possible Solutions: Make QoT easier to kill: Right now Bramble gives a hell of a lot of absorb (1200 at level 4), is reasonably cheap, and can be cast pretty fequently. Maybe that will help.
[Edit]Possible Solutions: Remove Uproot. This would make me sad. 
That being said, replacing uproot with some kind of damaging root that targets heros instead of buildings might also be acceptable and not totally gimp her (Actually it would be a massive nerf, since she can't kill things by herself).[/Edit]
Possible Solutions: Something more impressive that someone else will post that isn't typing things at 5:00 AM.
Now stop whining about Sedna and complain about heros that are actually madness.
[Edit] I also think it should be pointed out that this strategy completely ignores the totems. If the game dragged on (somehow?) I guess you could get them, but they serve her no purpose. Shamblers are also wasted compared to this build, as they die easily and don't kill towers as quickly/effectively. With shamblers wasted and totems wasted, there's no reason to get any ability that improves your minions, which is about half of her tree. One Possible Solution would be to make her minions relevant instead of worthless.[/Edit]
