(From the wiki)
When u import a ME 1 game save to ME2:
A portion of the character's Paragon/Renegade points (up to 190 each, which requires the bar(s) to be 50% full[1]) are transferred over.
◾Importing a level 1 through level 49 character will grant 1,000 XP (the player starts at level 2), 20,000 credits, and 2,500 of each resource.
◾Importing a level 50 through level 59 character will grant 2,000 XP (the player starts at level 3), 30,000 credits, and 5,000 of each resource.
◾Importing a level 60 character will grant 4,000 XP (the player starts at level 5), 50,000 credits, and 10,000 of each resource.
◾Having the "Rich" achievement from Mass Effect will grant an additional 100,000 credits.
◾The import bonuses will stack with the Mass Effect 2 completion starting bonuses (200,000 credits and 50,000 of each resource).
For a replay with a ME2 character (New Game+):
Keep all obtained weapons (including Heavy Weapons, but the M-12 Locust will not transfer), and armor in addition to the bonuses. A consequence of importing an existing Mass Effect 2 save is that the weapon specialization chosen in the Collector Ship mission carries over, and a new one cannot be selected. Another consequence is: paragon/renegade will start from zero, even if your character were a Rich ME1 character. And you can NOT change your class in a New Game+.
◾+25% Bonus Experience - More easily able to reach level 30 with a new character in a single playthrough. With all DLCs installed, it's possible however to reach level 30 in a single/initial playthrough (during the final mission), even if starting at experience level 1.
◾+200,000 Credits
◾+50,000 Iridium
◾+50,000 Palladium
◾+50,000 Platinum
◾+50,000 Element Zero - Will not have to scan for element zero at all.
◾+500 Fuel and +30 Probes - Existing Mass Effect 2 characters can carry over extra fuel and probes if the save file possesses the Extended Fuel Cells and Modular Probe Bay upgrades and both are fully stocked. The Normandy SR-2 will possess 1500/1000 fuel, and 60/30 probes following the Freedom's Progress Mission.
◾You will also be able to choose a loyalty bonus power from any of the squad member whose loyalty you earned through the last playthrough.