My camper has frameless windows, sliders (up and down, and side to side) and crank-out, and the emergency exit window. My previous 2 TT's had the standard frames. So far, as far as functionality goes, there's no difference.
Actually, there IS a frame, it's just more behind the glass, so the window looks like it does not have a frame.
I've had no problems or issues with mine, except for one knob on the crank-out window above the kitchen table that keeps unscrewing and falling on the floor. No matter how tight I make it, it seems to wiggle loose. Only one that does that!