Get meta data excerpts if available, otherwise use get_the_excerpt().

gistfile1.txt

if($instance['post_type'] == 'features'){
  			$exc = get_post_meta( get_the_ID(), 'feature_excerpt', true );
				if ( $exc != '' ) { 
			    	$exc = stripslashes( $exc ); 
			    } else { 
			    	$exc = strip_tags( get_the_excerpt() ); 
			   	}
			} else if($instance['post_type'] == 'feedback'){
				$exc = get_post_meta( get_the_ID(), 'feedback_excerpt', true );
				if ( $exc != '' ) { 
			    	$exc = stripslashes( $exc ); 
			    } else { 
			    	$exc = strip_tags( get_the_excerpt() ); 
			   	}
			} else {
				$exc = strip_tags( get_the_excerpt() ); 
			}
			$html .= '<div class="widget-slider-excerpt">' . $exc . '</div>' . "\n";