Google is still the biggest search engine, in terms 0f users, despite the others catching up a little. It has around 60% of all searches on the internet, and is the holy grail when it comes to optimisation and key phrase rankings.
The best and worst thing about Google for people wanting to succeed, is the fact that they try their very best to keep the search results pure.
It's the best reason because it stops the majority of rubbish getting to the top of the rankings by using spamming techniques. It's a bad thing because it means there is no easy fix, no rapid rankings, no magic formula to getting to number 1. That's right, pay £10,000 and ask someone to get you to number one on Google for a moderately difficult phrase and it just won't happen. Or at least it will happen for a week then you'll drop back down to number 132, and by then the cheque has cleared and it's back to square one.
Keep watching and I'll be posting some more blog on SEO later.