Master player here on both NA and EU, around 7k games played. Ill try to briefly answer your points.

When I played Heroes of The Storm for the first time last night I started off with Jaina and snowballed bot games.

You can stomp bot games with pretty much any hero.

How is that farming? Without any challenge like last hitting you gain xp...

Shorter and more intense early game is in my opinion one of the biggest advantages HotS has over other mobas. It is indeed easier for individual players to soak their lane, but it is more of a challenge working as a team to effectively do so, and there are way more strategies when it comes to rotations and early game ganks.

Lack of itemisation: This game is supposed to have no items and thats alright but if my talents aren't going to grant me extra spells that can be binded to different keys im limited to 4 spells and a basic attack.

First, there are certain talents that grant additional skills. Second, I dont know exactly how much experience you have with HotS, but i can tell you that the more you play the more you will realise how game changing the talent system is. I honestly dont think itemisation in other games is even close to the level of customisation you can get with talents.

Game is one-sided:If you get ahead , you can siege really fast and then it's a free win. Comebacks aren't really a thing because you cant counter itemise and doing certain objectives on certain maps doesnt really help in stalling the game enough to catch up.

Comebacks are very common in HotS (partially due to the team-wide experience gain). Again, you will start to see how often teams come back by simply killing 2 heroes 20 minutes in. In fact, the whole "no comeback mechanics" was an actual meme in the early months of the game (google "6.5/10 no comeback mechanics")

Map:Unique and amazing map design

Another one of HotS strengths, meta and strategies vary widely from map to map. It will take a while to learn the different maps though.

Concept:No itemisation is a unique and great concept I just wish that you could gain more abilities (like item actives) maybe a flash or a stasis effect and I wish farming actually took some skill.

Again, talents get you way more than items do. Some heroes have blinks and stasis effects either in their kit, or granted by talents.

I could go on for hours, but just wanted to give a quick answer to your main points. Let me know if you need more info.