I've read a lot of Dostoevsky and I'd have to say I've never noticed a difference in the translations. His writing is so plain-speak -- that is, there isn't a lot of visible stylistic flourish or linguistic experimentation -- that I imagine the translator's job is very straighforward. Just pick up whichever book is nearby and it'll probably be fine.
The only bad experience I ever had with a translator was with Kafka's "The Castle". I read it in a cheezy paperback format, published about 20 years earlier, and I loved it. One of my favorite books -- read like a dream. Then a couple of years ago they announced a new, highly researched scholarly "authoritative edition". I picked it up and, even though I can't pinpoint exactly what was wrong, the fun was all gone. Unfortunately my old paperback had fallen apart and I can't find a new copy.