Don’t like Twitter's new photo preview? Same here. Fixed.

twitter-photo-preview-fixed.user.js

// ==UserScript==
// @name        Disable Photo Preview on Twitter
// @namespace   http://example.com
// @description hacked with love by @akuhn
// @include     https://twitter.com/*
// @version     1
// @grant       none
// ==/UserScript==

function addGlobalStyle(css) {
    var head, style;
    head = document.getElementsByTagName('head')[0];
    if (!head) { return; }
    style = document.createElement('style');
    style.type = 'text/css';
    style.innerHTML = css;
    head.appendChild(style);
}

addGlobalStyle(".with-media-forward .cards-base .media-forward { max-height: 0px; }");
addGlobalStyle(".with-media-forward.opened-tweet .media-forward { max-height: none; }");