There's a great Radiolab episode that covers exactly that: http://www.radiolab.org/story/translation/
I'm reading Foucault's Pendulum right now, and even though I'm absolutely loving it, part of me feels like I'm missing out by reading a translation. The other part of me wonders whether those who read the original work missed out by not reading this translation.
In general I often feel the same, but in this particular instance it might make you feel better to know that William Weaver's translations are widely lauded.
Eco famously said Weaver's translation of The Name of the Rose was "much better than the original". :) And I've always found it pleasing to wonder if that might not even be true. One thinks of a translation as being necessarily inferior to an original, but depending on the two writers involved, there's no ab initia reason why it might not be better (for some given definition of "better", anyway - clearer, more accessible, more profound, etc).
Particularly if you start with a book centered about plot, structure, and other "macro" properties of good literature, and apply an author that excels on the "micro" structure part.
Jorge Luis Borges, or Vladimir Nabokov, with their great command of vocabulary, come to mind. They are also great authors that dealt with several translations. Borges, particularly, stated that translations could improve the original, and modified his translations where he deemed appropriate.