Anaxagoras said:
What are the effects of this?
Based on a realistic appraisal of British policy in North America since 1783 i'd say:
1. New Orleans is returned to the US on condition that it is made a freeport and that the US recognise that British subjects have a right to trade and reside in lands acquired under the Louisiana Purchase. In OTL the 1783 and 1794 treaties had given equal access to both nations to lands around the Mississippi basin, however the US reneged on this agreement by claiming that this did not actually include lands acquired under the Louisiana Purchase.
This may have led to greater efforts by the British to develop the St. Lawrence as an major artery carrying goods in and out of the mid-west and an influx of British settlers to the west of the US.
However due to the declining economic importence of the American fur trade and a lack of imperial interest in north America after 1815 it seems more probable that ultimately very little changes from OTL.
2. Britain secures a favourable and firm agreement on the Maine boundary.
3. The US is to assign over a significant portion of the Ohio territory to the Indians. This reservation forms a buffer running to between the US and Canadian boarders. Whilst it remains part of the US it is effectively a demilitarised zone which the US uses to dump indians cleared out of lands further to the south.
4. The US is forced to accept and enforce a reciprocal right of stop and search on the high seas. This actually works to the Americans advantage during the Civil War as the British are forced to accept US blockade of the Confederacy.
5. Both sides are to sign a trade agreement giving each other most favoured nation status and removing tarriffs and restrictions against British goods. The US also has to recognise that as of 1783 it has no legitimate right to trade with British colonies.