I have had one Enterprise rental in the last year (was a one-way whose cost was 1/3 of any of my preferred companies). Wasn't sure what to expect....

1) After having go-straight-to-the-car with my preferred companies, hated having to stand in line.
2) Annoyed at the upsell attempts.
3) Found the whole escort-you-to-the-car and spiel about the car's features and upsells (again!) annoying.

My impression over the years is that one of Enterprise's niche markets is the same once-every-two-years travelers who fly Southwest and love it because of no checked bag fees, no assigned seats ("Gee, we can sit anywhere we want!"), and a continued perception (no longer true but a real triumph of WN's marketing over the years) that Southwest always has the "best deals."