Spoilers!
Just played the demo. Overall I quite liked it. There were some funny parts, like at Oaks lab and one of the children's houses, and the graphics and music is ok. However, it does feel quite incomplete, with a lot of errors and some bad tile choices. I only played up untill Oaks lab as it got slightly boring trying to find the Pokemon, then dying.
Errors
Your house:
You can go over and under the bed.
You can't go behind the tv.
Up and downstairs is a bit bad.
When you talk to your mum, she heals you, but there's no music.
Lab exterior is 3rd gen.
Town:
In the house to the left of yours, it's 3rd gen.
So is the house below, which inside the maid doesn't speak.
In front of the house is a desaturated lamp post, which doesn't match with the saturated-ness of the game.
So is your house.
Shadows aren't semi-transparent.
At the far west house, you can go up to the door, although it's locked.
In battle:
Your 'mons base is smaller than it should be.
When you go up a level, about three quarters horizontally through the box there is a one pixel see through vertical line.
Bit past the stairs out of town:
At the left, above the honey tree, you can walk over the mountain tiles.
Just above the, the grass goes under the mountain...
Route 1:
Going up and the the steps brings you one tile too far.
I'm either incredibly lucky, or there aren't any 'mon in the grass.
Mew battle:
"Wild Mew sent out Mew!"
After the battle, the Rocket grunt just appears.
As well as all of this, there are a few grammatical errors. Like how people use too many exclamation marks, miss spell some things and don't say Pokémon, but Pokemon.