LaGuardia has had a reputation for quite a while of being a low-quality, too-crowded, run-down airport. That reputation was well-deserved up until recently, but the airport is now undergoing a massive overhaul, and the new facilities that are open to date are actually pretty nice now.
Terminal B ticketing lobby
The airport still has a few rough edges. In particular, it would massively benefit from a consolidated rental car center, as getting a rental car now currently requires two shuttles (a shuttle to Terminal A, and then another shuttle to a parking lot somewhere in Queens). It also doesn’t directly connect to rail transit like JFK and Newark do. There are indications that both may be addressed, but for now, they’re minor pain points.