I am in Poland until end of August with my DR 650.
Poland is not dangerous. Just be careful for theft. Do not leave stuff on your bike if you're going sightseeing. Also, always preferable to put your bike in a garage or safe parking overnight, and chain it. But that applies to almost all countries. There's bike thieves everywhere.
As mentionned before, the roads are quite often grooved because of heavy truck traffic all around the country. Truck drivers do move over to let you pass. Only real danger are impatient drivers trying to pass; they have a tendency of tailgating that is a bit annoying.
On small countryside roads, be careful for slow tractors, cyclists and wandering dogs in villages.
Otherwise, lodging and food is quite cheap. Fuel available all over the place. Beaufiful country with a lot to offer. Do not miss Krakow, Wroclaw and Gdansk.
Note that because of the lack of highways, your progression through the country will be much slower than, let's say France or Germany. Keep that in mind when planning your trip time wise.
[This message has been edited by PaulDR650 (edited 13 July 2005).]