My navigator hit rank 2 and is on the way to rank 3. Now I wonder how useful the talent warp sense and later improved warp sense are. Has anybody taken them or some experience with the two talents?

I didn't take them, they can be very useful in pursuit situations, but imo the application isn't worth the xp unless you build a specialised character (bounty hunter style). Basically they allow you to use an extra action each turn for 1k xp, but given the vague description of psyniscience's effects, the use depends greatly on your gm.