More of a 3.5 star, but I'm feeling nice.
Last year, the Titans united (see what I did there) to deal with Starfire's sister, because that's who they were fighting in the third season of Titans. Now that the TV Titans are battling Brother Blood and Mother Mayhem, the comic Titans are back again to do just that. Corporate synergy, everyone!
But honestly, this isn't bad. Tim Drake wakes up in an alternate reality caused by a Brother Blood spell, and must de-program his brainwashed Titans friends and put things back the way they were. It's a decent plot, if a little heavy on the double-and-triple crossing (I lost track of what side Raven was on more than once), but it filled the gap nicely while DC got their other Titans book from Tom Taylor off the ground.
The real draw for me personally was Lucas Meyer's art, which is just lovely. It's fully formed, always detailed, and beautifully coloured. I couldn't even say that it's particularly unique in terms of style, but it's so well polished that it manages to look like it is, if that makes any sense.
Titans Tie-In, I mean, United, is fun, if a little confusing. But it sure does look pretty.