IF you are traveling much within Central America, you do not have much choice. Their loyalty program is good for getting upgrades as an elite and miles redemption on Taca. If you want to try to use their partners for rewards, you may be in for a long fruitless process.
Otherwise, their planes are new, all airbus except for a few embraers that are being added for shorter hauls. They have some very good people working the airports and the flights and some questionable ones making some of the policies.