My basic attitude is that in heroic fantasy where most characters are one type of ideal or another, it's not so much a girl being oogled or not that makes her a "strong character" but how she reacts to it. There is no one "right" way to do it and be strong, as a girl can be strong doing everything from ignoring it, to giving scathing put downs, to playing the temptress, it all comes down to how well written she is and what she does other than act as eye candy (or if she's eye candy, how she goes about pulling that off, since that can actually be empowering as well).
That said, I'll say that at 39 I'm just old enough and a big enough nerd where I can say I both actually read the old Black and White comics, and played the Palladium RPG based on them (fairly heavily in fact). While I am in a distinct minority, I actually felt that version of "The Turtle" was actually better, not so much because it was darker but because it seemed to be better put together, thought out, and constructed as far as such things go. At the time The Turtles were hitting the cartoons and became a huge success, beyond anything they did in an obscure comic book, I was getting smart/wary enough to be sort of put off by the whole thing, especially seeing as it was pretty easy to see the mass merchandising involved, and some of the things like the "Turtle Van" just outright annoyed me. The Turtles as a concept seemed to always work better to me as a sort of urban legend, and being fairly frightening monsters in appearance (I mean seriously, a humanoid mutant turtle would be kind of freaky, they had things like that in the D&D monster manual... and I believe it's pretty close to the description of a Kappa from Japanese mythology to boot). While they made some mild pretensions of hiding in the sewers, them dragging a reporter around while they tear up the streets in a brightly colored van covered in shells, with guns hanging off the side, just never seemed right to me.
At any rate, I'll be blunt in saying that I do not think the version of "April" from the cartoon could really be considered a strong female character. Overall it always seemed to me that she was extraneous to the plot, and while she wasn't always a damsel, she seemed to largely operate as a foil and build in plot/information source. While some attempts were made to do things with her, and she was always there, I always felt she was kind of a part of the scene dressing.
In the old comics, April wasn't present as much, but she actually served an important role by acting as a sort of bridge between normality and the fantastic. Her initial background aside she was fundamentally just a girl with an antique shop who was decent with computers and once ran into a nut. By all rights she could have walked away from the turtles and would have every reason to do so, but she didn't, compared to the comic version where one can argue that April's entire career is based around the fact that she knows the turtles, and honestly I've kind of wondered if she would have really ever been anyone without them. What's more in the original comics things are pretty dark, people die, the bad guys are not always portrayed as being total buffoons, and the turtles are pretty scary looking (and at least one of them is arguably a sociopath... yes Raphael I'm talking about you). In the cartoon the bad guys are almost laughably incompetent, the turtles are a bunch of brightly colored pizza swilling clowns who it is hard to be scared of (being re-designed to appeal to kids), and nobody does... and the whole series rolls like that, being a cartoon everything is magically sanitized. It's not like your going to see a truly brutal melee, and have the turtles, themselves actually cut up/injured standing in the middle a pile of dead ninjas and wonder about how they are going to dispose of the bodies...
The point I'm getting at here is that I think the B&W version was actually a stronger character even though she did less, and was less active for a lot of it (though she does hook up with Casey Jones and even dons a hero mask briefly). Heck she even keeps doing this stuff after she's rendered sterile. Indeed I think in this case less was more.
Now, as far as Megan Fox goes, I have a little more respect for her than a lot of people do. She seems to be a decent actress, even if she has a tendency to say the wrong things to the wrong people (which I can empathize with). She's smoking hot of course, and you can't blame her for using that while she's got it (or directors for exploiting it). I actually suspect she's someone who will get more respect 10-15 years down the road when her looks start to seriously fade (though she seems like the type who will always been attractive for their age group). Mind you I don't think she'll make any "best of all time" lists, but it seems like she's decent enough where she'll be around in one form or another for a long time.
I'll also be blunt, Megan fits in with the old B&W version of April. April being a redhead started with the cartoon, and while that's the more well known version, I will say that they seem to have been going for a look more similar to the old B&Ws, with the turtles being a lot "scarier" looking as well for example, though it still drew heavily from the version most people know.
I won't likely see the movie until Netflix though, simply because no matter how much money it makes The Turtles drove me out of the theaters a long time ago.