The following is a slightly edited version of my once-unpublished review of this game from 2017.
Rule of thumb: if Traveller's Tales develops a LEGO adaptation game in 2012 or later, and even if it may not look like it'll suck at first, it's going to suck. I've played this game and LEGO Dimensions to prove I'm not lying.
First of all, LEGO Batman 2 sounded better than the first game, what with it adding in other characters from the DC 'verse into LEGO Batman. Not only that, there were several other things--a fully explorable Gotham City, the aforementioned non-Batman DC characters, new suits for Batman and Robin to use, this game being the first LEGO adaptation game to use actual voice acting...it felt like the gift that kept on giving.
However, it didn't just feel the same compared to previous LEGO adaptation games, because some drastic changes were made for this game and every future release. You know those times when you beat a level in the older games, then got to buy one or more characters that you witnessed in said level for use in Free Play mode? Unfortunately, you won't be doing stuff like that here--instead of having a place to buy new characters from, you have to rack up as many Gold Bricks as you can from doing things like searching around Gotham and doing certain puzzles within the city or beating levels after collecting lots of studs to get said Gold Bricks, then use them as well as a certain amount of studs to buy a character that you can use in Free Play mode. Oh, and you also have to find the exact locations of these areas where you can use your Gold Bricks to unlock new characters.
Here's an example of how to unlock a character--from what I remember, to unlock a policeman for use in Free Play mode, you have to rack up fifteen Gold Bricks, then assemble a doorway made of said Gold Bricks not too far away from Arkham Asylum. You then spend 25,000 studs to buy him, and now he's in your collection.
There are other methods of unlocking characters, too. Beating up several generic mooks that randomly show up, like the Joker's goons and Lex Luthor's LexBots (or whatever they're called; it's been awhile since I last played this, and I returned my copy for reasons explained later), then buying said mook you beat up a bunch of earlier is one example. Another is activating one of many terminals scattered around Gotham, finding supervillain X (there are many examples of this) near said terminal, winning a battle with them, and buying them for your collection if you defeat them.
They also revamped unlocking extras, too. If you've played a LEGO adaptation game before, then you'd easily know of Power Bricks. Find one in level X, then buy it with amount of studs Y so you can use extra Z at any given time. In some games, the Power Bricks are replaced with other things; for example, LEGO Indiana Jones uses Parcels in place of the Power Bricks you know and love, and you have to find the Parcels and drop them in a nearby mailbox in order for you to buy them later.
Of course, that's not what I'm talking about here--rather than find them in the game's various levels, in LEGO Batman 2, you have to unlock extras by searching around Gotham for the Power Bricks--now going by the more generic moniker of "Red Bricks", but I'm still gonna call them Power Bricks--then do certain things to get said Power Bricks, such as play minigames that involve you controlling a miniature vehicle that destroys other miniature vehicles, or unlock/break open a crate that only the Riddler/etc. can unlock/break open. You can then buy the Power Brick after doing whatever you did to unlock it beforehand. I miss searching every nook and cranny of a LEGO adaptation game's various levels just to find a Power Brick.
What also isn't the same to me, however, is the voice acting. Remember when pantomiming was a thing? I do. Sadly, now it's a thing of the past, because, starting with this game, every character has actual voices now. While I may like this change, for some reason, I simultaneously dislike it, mainly because it doesn't feel the same as previous games.
In short, Traveller's Tales completely revamped how characters and extras are unlocked, and they added voice acting. Compared to their earlier titles, things aren't the same as they used to be.
Now that I'm done talking about the drastic changes Traveller's Tales has made to their LEGO games I know and (sorta) love, it's time for things to get worse.
One week after I bought this game, I beat it. Little did I know that things got real glitchy from that point. Things started off tame, what with me experiencing heavy lag at one point while I tried to get a Gold Brick. After that, it got worse. At another point, the music seriously glitched out, causing me to reduce my TV's volume until I changed the music again.
Once I saw those glitches happen...later on, the game did it. It went up and froze on me while I tried getting one of the Red Bricks Power Bricks. From there, I lost all of the patience I had for this game, refused to play it again, and returned it after another week.
Oh, and a few more things--the tone that played when the game froze was the same tone I had heard several times in LEGO Dimensions, and did I forget to mention I played the Wii version of LEGO Batman 2? I could've used a different console version, but I'm certain the version I choose will be a buggy mess, too. Want proof? Well, I had to take a look at most of the ports' GameFAQs boards. Several of the topics in each board mentioned glitches within this game. Some of the glitches made getting 100% near-impossible, making you somehow PERMANENTLY lose a minikit/Gold Brick/etc. despite grabbing one in any level/wherever else, for instance.
The sudden bugginess made me so disappointed, I gave up on the game. I expected this to be fun, but nooooo, Traveller's Tales had to get the most incompetent bug testers ever! I also forgot one thing--again, I played the Wii version, but, unlike this game's predecessor, this version of the game doesn't allow me to attack by swinging the Wii Remote around, instead making me mash B to attack. Screwing me out of a more convenient method of attacking; that's another sin committed. The game's also pretty quiet compared to some of the other games I played at the time, so I had to have the subtitles on, as well as my TV's volume being at a high level, just so I could actually hear things.
In short, if you want to play LEGO Batman 2: DC Super Heroes, please don't if you can't stand horrible bugs like me. I also looked up GameFAQs' boards for LEGO Batman 3: Beyond Gotham (this game's sequel...duh!)...and noticed that even in those boards, there were many mentions of the game being glitchy!