Bad
Flimsy bottom metal where the action screws engage. Benefits immensely from pillars being installed in the stock.
Plastic bolt shroud and bottom metal/magazine
One-size-fits-all action length
Not much aftermarket support (because it doesn't need much), which is disappointing for tinkerers.
1) Not flimsy, supported inside with steel.
2) Reinforced polymer, show me either one you have personally broken.
3) Discussed above.
4) All you'll ever need...http://www.tikkaperformance.com/