Has anyone here won yet? How long did it take? How did it feel? Any general tips or hints?

I have won Single Scenario's on Expert and Tiny and Small sizes. Feels pretty good but sadly your hero does not get very high because of the size.

I have not really tried the Campaign beyond a time or two.

I've won- rather easily- on a big shard w/ 6 enemies, at Beginner level. Once you have 3 heroes lvl 20+ it's a walk in the park.. Have to spice up things a bit !
Didn't go far into the campaign (5-6 shards), it's a bit too repetitive/long for my taste...

I play single scenarios on expert.
I win about 50% of those at the moment. The BIG Problem for me was to unlearn what i had "learned" playing about 10 games on beginner. I still missjudge what i can take on at any given moment based on that. In addition to just being wrong i mean ^^

Winning on expert still feels like a major accomplishment for me and the best tip i can give you is not to play on lower difficult settings to learn. Because you wont. You will have to relearn things completely from scratch.
Tactics that worked well when enemys have 45% hp dont work when they have 100% etc.

And dont be afraid of loosing...it happends.