It was a really big deal for me to become a citizen, as silly as that may sound, and I am very, very glad I did it. It was absolutely no problem to remain a US citizen. When I renewed my US passport a few years later, at the embassy I was asked whether I had become a citizen of any other country, and I said yes, the UK in 2001. They said, that will be 80 dollars please, or something like that.
Having the freedom to live and work, not only in the UK, but in every country in the EU is a tremendous bonus for me. I actually work a good bit in Germany and believe me, the EU passports queue is quicker.
But I feel happier about the fact that I can vote and that my opinion "counts" here for something. I also think of it as my own tiny contribution to international relations - I have ties to two countries and two continents, and that colors my political "agenda" and my life-outlook.
And by the way, the "oath to the queen" has been modified a bit under the new citizenship ceremony. I believe it goes a little further than that now, and includes things like
"I will give my loyalty to the United Kingdom and respect its rights and freedoms. I will uphold its democratic values. I will observe its laws faithfully and fulfil my duties and obligations as a British Citizen."
The UK IS a very free society and its values are very democratic, indeed, monarchy notwithstanding. These are values of which we can be proud; it is the birthplace of democracy in a true historical sense.