I love snuggling up with my plumbing.
I agree though. You'll want to go through it and very thoroughly check it out, snug up the fittings, test everything, fix anything that doesn't work. Personally, I recommend you do the fixing part yourself, not at a dealership. It stands a better chance of coming out right that way (unless what needs fixing is replacement of an appliance or something major).
Check the seals on all roof penetrations (skylight, vents, etc. - anything that goes through the roof) as well as the seams at the roof edges. Roof leaks are the worst. Also check the caulking around wall penetrations (lights, mainly).
My trailer had very few issues. A bad water pump, some loose plumbing fittings, and the through-the-wall AC had been poorly setup.
Advice: After you've loaded up, stop off at a Cat Scale and get true weights.