I think the 2012 Turtles combine a lot of elements from the previous two shows, but lean more toward '87 Turtles in their delivery and not being too serious.
I'd say the current series is closer to the first cartoon in tone and humor, but closer to (and surpassing) the second in quality. The thing about the '87 show is that it went pretty consistently downhill. Its very first episode was the best it ever did. The rest of the initial 5-episode miniseries was also pretty good. After that, each successive season got dumber. I gather it rebounded a bit in its final season, tried to get more serious and darker, but I'd lost interest by then.
The '03 series was pretty good in its first five seasons, but it was clunky in some ways, both in writing and production values. The current series is sometimes pretty dumb, but it's wildly imaginative and bold in execution, it has terrific design and storyboarding, and it has a really good voice cast, probably the best of the three. (Although I wish just once we'd get a Shredder actor who actually knows how to pronounce Japanese words.)
Then there's
The Next Mutation, which is a whole other conversation... (Honestly, I'd be curious to revisit that, but it's hard to find. There are some episodes on one of my On Demand cable channels, but I'm waiting for them to cycle around to the start of the series, and I only occasionally remember to check.)
I'd like to see the '03 Turtles make a reprisal, since there last few seasons weren't that great and the series as a whole ended with lingering threads.
I think you mean a reprise, unless you're saying you want to see them retaliate against or seek redress from the people responsible for the last two seasons...
Hun was also an original character from the 2003 cartoon.
Oh, I figured he was from the comics, given how faithful that show was in its early seasons. That's interesting. So that's at least two characters created for the '03 show and incorporated into the current show, although reinterpreted enormously in both cases. (The current Hun is basically a CGI Bruce Lee.)