We stayed at El Atlantico as part of a medical volunteer trip for 7 nights and were prepared for a rustic experience. It's a schlep from Guatemala City (~3-4 hours), but conveniently located for day trips to Zacapa, which is what we were doing.
I was pleasantly surprised by the good service, lovely pool, and free wifi (in the lobby). The cabins were clean and always well made, have AC (amazing!!), and lukewarm shower water (which is appropriately refreshing for the climate). The food is fine - fairly typically Guatemalan, heavy, but a good variety of options. Drinks are cheap and unremarkable (can't go wrong with Gallo). Nice grounds with plants and animals, but beware the bugs!! They will bite you if you're anywhere near the grass or pool.