Honestly, it depends on what features you'd actual use if you upgraded. I have an AppleTV, so going from 4.2.1 to 4.3.2 (4.3.3 wasn't out and I haven't upgraded, just installed untrackerd) made sense for me. That, along with personal hotspot (activated through TetherMe) and faster Safari it was a no brainer for me, as they say.
For you? I don't know 🙂