Sorry to hear it got away like that on the first flight. Also concerning the trim issue, did you make sure and calibrate it prior to flying? That's the so called Restart Function on page 8 of the owners manual. And make sure the quad is on a flat level surface when you do the recalibration.
As...
The Syma X5C is actually a very nice quad. I started with a JJRC H8C and thought that was nice but it's actually fairly heavy and tends to eat motors. The X5C is a nice, light quad with a good run time and is stable and fun to fly - I think you made a good choice. As for immediately starting...