Qvixote,
Congrats on your offer from LEA. While I do not know much about LEA personally I have heard good things about flying the Mustang. It is an entry-level jet with very advanced automation (Garmin 1000). It should be a great entry-level position with an opportunity to fly all around Europe and into LCY.
Did you seek out LEA or did they find you? What sort of qualifications do you have and did they mention other aircraft opportunities within their fleet down the line?