Weight / Fat loss

Just signed up for a gym, did my first session with an instructor (I've never been in a gym before so am a complete and utter n00b). Instructor gives me 4 mat-based exercises, tells me to do 2 sets of 10 reps each, then tells me to beat it. Whole thing lasted about 20 mins. Is that really it? Was kind of expecting something a bit more intensive and / or involving the Shit What's In The Gym. Have I got a duff gym or is this what they're supposed to be like for a first session?
The freebie instructor session when you sign up to a gym is just so that the instructor can try and sell you more sessions. It's otherwise pointless.