I have been researching used E91 328i's, so I have a few thoughts. You can get tons of info on the Bimmer forums, but take it all with a grain of salt. E90 BMW 325i's can be very reliable cars as the BMW has been refining the reliable inline 6 for several generations. Just keep in mind that any BMW getting into high mileage will have expensive maintenance that you need to stay ahead of. They are high maintenance, but not unreliable......... I wouldn't do it unless you are ready to do a lot of maintenance yourself or have a great local independant BMW service shop to work on it.... will save you lots of money.
You might note in your search how many used BMW's are for sale with 98,000 miles. This is because many ditch before the 100,000 mile service. You might budget $2k the first year for the 100,000 mile service and other neglect that you might run into. Could be far less with a good indy shop. I think these have timing chains and not belts?
One more thing, if you can try to bring the car to an independent shop before buying for a third party inspection......... Good luck!