1. Terrain is plain and flat, not only DotA-ish.
2. Heroes do not go to attack/help their minions when they are attacked. If you take a look in the base for items, the hero might not be attacking at that time instead standing near a ranged minion who attacks or is attacked.
3. Some heroes do not have hero glow. You could add that:
How to add Hero Glow without Modeling
4. Only one game mode.
5. You could change the tower models or colour or size for each of their superior.
6. After a team destroys the Forgotten One, which by the way is closer to the blue team (well, the mine is closer to the red team), the buff is pretty strong. At least it's temporary.
7. From level 9th onward, experience gain is slow at least on creeps and minions.
8. Do buffs stack? I had two Golem Wills on my hero.
9. Hunter's Haste has the same hotkey as Toxic Fog: W (even the text says it).
10. Not sure if intelligence heroes should have a shorter range than agility heroes. Rul'drok (this guy also has average walking speed with boots on) has 475 while Xet has 500.
11. What about if one of Mannothor's spells slows attack speed instead of movement speed?
12. Hex Rod+Blink=troll face.
13. Ra'ax' spells don't cost mana!? But he has 150 of it, I guess for pedestal spells and for enemy heroes to use spells on? This hero is similar to the ghoul of DotA.
14. Tryal's Slow Poison has the same icon Xet's third (passive) spell. This guy also has Blink (+Spell:Blink; also they both have the same icon). Hallucination cannot be used on other units than heroes.
15. Gruyu's 3rd level Headhunter's Blood regenerates quite a lot in a period of 1 minute.
16. Calypto is green not purple as his icon. Maybe you could either change the hue of the icon or make him purple during Into the Void (the problem with this spell is that it can get you trapped between doodads until you use it again).
17. Corrosive Sting's icon=Cripple's
18. By the way, Recall has no cooldown.
19. Some spells like Flame Strike are just copies of Warcraft III ones.
20. Jinzo's life steal and critical strike+items which give life steal and critical strike. Imagine that. He already has very fast attack speed with the boots that give attack speed.
21. Towers have a buff called Fortification which has the same icon as Emilio's Divine spell.
22. Defensive Strike's icon=Imbued Sword's.
23. Sieg Vein has no soundset. It's weird that heroes like this one start with 1 armour and those like the one with the Arthas model which is a strength hero, starts with 0. Sieg Vein's icon isn't appropriate. His model hair is not blonde.
24. Maybe another model for Grum because he/it is basically a copy of the neutral golem with a different colour.
25. Battle Trance's icon=Headhunter's Blood's.
26. Glyph of Double Edge's with Crusader Strength.
27. Vine Trap affects a higher zone than the one shown when casting it. This hero, especially the first spell, reminds of one from DotA.
28. Blade of Hatred icon=the third spell of Jrono. Fan of Knives icon=another one from another hero (can't remember right now). Blinkstrike is basically that other hero's blink (Jinzo, I think) but with the exception that this one can also be used on allied units. Oh yea, as with Ra'ax, spells cost no mana but the hero does have 150 mana (possibly for pedestal spells). It might be necessary to increase spell cooldown for late game.
29. Guardian Impact icon as other Blink spells. Does Nivash have a soundset? I guess, Nearby's Spirit AoE is too small.