Try to work on your fonts and the way you show the texts. At some points,i have to push myself to read what it`s typed... Other than that, you play too much with color corrections,and from there,you are losing the realistic look. Its more like an animated animation,if you know what i mean
I like your grading there. Nice effects especially the meteor impact at the end.
very nice! Interesting to see the different effects.
By the way, that is called simply the clocktower, not big ben. Big ben refers only the biggest bell inside the clock tower.
I'm not really sure what you're after posting this. If you want advice on how to improve your FX, try posting on the FX section. If you're asking how good they look - erm they look like FX.
The openng FX look just like you've dropped a plug-in over a clip.
The castle ones look a bit better, but not at all realistic.
I certainly couldn't do it myself, but if i could, I wouldn't post this as an advert.