The heat and fan are the only "major" issues, and they're kind of exaggerated, though they do mean gaming performance isn't extremely high. Though a fanless design would mean drastically worse performance. It's just a natural trade-off, my only real complaint there is I wish it didn't trigger the fan's low/medium setting when I'm watching streaming video.
Battery life is fine IMO. It's high end laptop mid end tablet battery life. Not sure what people are expecting, considering the display and oomph it has it's quite fine.
There's really no "flaws" IMO so much as trade-offs and a device like this will always have them.
I can't see a 14" version working as well. This is the size of a legal pad for a reason, it's pretty much right as the size boundary to be holdable with one hand.