I rather like it!
It’s definitely a favorite of mine, probably helps that I think Suzie is a great Character (both thanks to the nice Script and especially Indira Varma’s great Performance as the Character). What this Story does with Gwen is great! The Plot as well certainly doesn’t disappoint! Sure, it could technically do more with it, but what it does with it already brings out some great Character Drama. Furthermore, I do think it’s a very good Story for Torchwood and exploring their Inner-workings very well! Really, I don’t think I can find many Complaints about it, besides maybe a few Nitpicks.