Would you say it would be a good purchase? I've always enjoyed Diablo, and the Infinity Engine games, and Xmen Legends on the PS2, and Freedom Force looks like the same type of game roughly.

So, recommend? Or alternate suggestions?

I liked the FF games quite a bit. The characters are perfectly campy, as is the dialog. Combat is fun, with enough superpowers to keep things interesting. The experience system works because you don't level-up so much as simply spend experience points as you go. You get a wide range of character types to play with, and wide variety of powers.

You eventually get choices of new heroes to add to your team, and that makes for one minor weakness - toward the end of the game you might find that the heroes you picked are not particularly effective against the enemies you face in the last few missions. That can make those missions all but impossible to beat. Without tossing out spoilers, just remember to choose heroes that will give you a variety of attack types (mental, radiation, electrical, etc) to help cover your bases.

After you win, play back through picking different add-on heroes, or maybe change the powers that you buy. There is also a sort of danger-room mode where it's just combat without a specific mission goal beyond clobbering the bad guys. Lots of fun there, too.

Myself, I liked the first installment a bit more but they are both a lot of fun. Hard to go wrong at 6 bucks.

HereForTheBeer summed it up quite nicely.
I'd add only that the game is neither like really like Diablo nor like the Infinity enginge games; it's a tacical RPG with superheroes, which, by the way, doesn't take itself seriously at all, which is a good thing for this game.

So quite a bit like the Xmen Legends and Marvel Ultimate Alliance games then :P

The X-Men Legends comparison is a fair one and if you liked that game, you will probably thoroughly enjoy Freedom Force. However, just be aware that FF is far more "point and clicky" than XML and its descendants are, so don't expect the same kind of controls with the FF games.

I've never played those games, but from the titles I guess it is like those.

I liked FF. They didn't really made me think of Diablo, even though they're the same genre. They're still fun games, though.

Check out Space Wolves.

And Freedom Force Vs is an excellent game with bundles of charisma and while it certainly isn't necessary i would recommend grabbing the first installment and then purchasing the second on GOG.

EDIT: I meant Star Wolves

The original FF is great fun at first, but it loses all momentum about two thirds in and starts dragging horribly. I absolutely loved the early parts of it and hated the final act which seems to take forever.

Haven't played FFv3R yet precisely because of that; I'm afraid it will turn out to be more of the same stuff. But they might have fixed the pacing in that one, I don't know.

I also liked the Freedom Force games. The combat etc. was nice, and I especially enjoyed all the humour that came from parodying old superhero comic cliches. You can also create your own superheroes, with lots of skins available on fan pages, so you can import a custom Wolverine or whatever in your games.

[minor spoilers ahead]
In the original Freedom Force, I've only played to the level with the giant robots (in the part where they go on a rampage on the top of the tower), which seemed to be virtually unbeatable to me; only Man-O-War had any decent electric damage, and he used up his energy quite fast, so I don't know how dragging the rest of the game is.
I tell you this because in FFvTR, on the other hand, I found no such snags, and also, I didn't feel it got slow/boring at any time, so you might enjoy it better than the original.

[minor spoiler territory continues]
You were lucky, then, because it's precisely after the robots when all goes to hell. The setting just stops being inventive; everything that follows is generic, lame and long. Not to mention that the final sequence forces you to fight all of the previous bosses of the game once again, for no reason at all.
But yeah, the flaw was pretty obvious, so it's quite likely they fixed it for FFv3R. I have the game already, so I might as well give it a try then.

You get about 2 dozen characters to choose from. Some are automatically given to your team as the game progresses, and others you'll have the opportunity to purchase. In any given game you won't have access to every single character since you don't get enough points to buy all of them. You get to take up to four characters along in a mission (some missions will limit you to a smaller group). Sometimes the game chooses who you bring, sometimes you choose all of the slots, sometimes it's a combination of the two.

Customization of the pre-made characters isn't very deep, but it's exactly deep enough for this game. Each character has a fixed number of powers that you build up by spending experience. Some powers require that you max out some lower-level abilities before you can buy them. For instance, you see that Character XYZ has Ability B that you want to get but you need to buy three levels of Ability A first. This simply means that you'll have to use that character a little more often to get more experience to buy that new power sooner. IIRC, even the characters you don't bring along in a mission still gain a bit of experience. You can also buy higher stats but I usually went for more powers unless I found a character seriously lacking in something like speed.

So, pretty much, computer Xmen Legends.

Awesome.

This, indeed, shall be my next purchase.

Thanks to everyone who has helped!