I for one never watched Babylon 5, so I didn't have that influencing how I perceived Tomalak. Based on what I saw in The Enemy, The Defector, and All Good Things I saw a a competant Romulan officer in command of a warbird who had some sort negative opinion of Starfleet/the Federation.
So while the novels present a somewhat different take on Tomalak, it's not one I am against either.