Just wondering, does the DLC for this game really make the game more enjoyable or is it actually better to play first time without DLC (such as for more challenge)?

Does the DLC make things too easy for advanced RPGers?

One word: Disable.

Edit: Hyperdimension Neptunia isn't among the hard RPGs, so DLCs aren't really necessary.

Only the Allowance(start with 1m or so credits) and Histys begginner items(start with some extra healing items) dircetly make it easier.

Plutia, Peashy and Histoire are pretty OP when you get them, but you can just activate the DLC and not put them in the party. Later on, Peashy and Plutia still have highest STR/INT, but aren't as OP anymore. Histoire gets a lot weaker later due to not being a CPU.

The Dengekico DLC is just extra costumes,.Additional content is for postgame(+300 level cap per and content for these levels) and FFF collab adds 1 event for level ~70 IIRC. Drops the 3rd best Nep weapon and becomes afterwards an Arena fight great for powerlevelling.

And that event can trash you if you are not prepared for it. I lost some progress due to that the first time I activated the event. >.<

Really useful to know (especially about which characters are OP, and aren't as OP later on). I read elsewhere that it was like 100,000 credits and someone suggested tweaking one of the game files to change the value to 30,000-50,000 credits instead, to allow things to be more challenging. I haven't played the game yet (purchased it with the DLCs today) so I have no idea whether it really makes much of a difference having the extra credits or not.

Well... for sure it would be usefull for buying stuff... You could spend it all on costumes that don't change mechanics/stats, but I myself turn it off, always. You will still get a lot of cash, and most probably you will be grinding to level up, so it's not really needed for start, and I always feel bad about those kind of advatages, even if they are small. Arena is different, cause you still have to wrestle it yourself, and additional characters... well, it's more of a wink to later entrances of the series, that's why I keep them in an anctive team, while they DO make it easier. Especially Peashy - she's the literal tank in the team thanks to her HP.

You could literally spend the entire 100k DLC cash on one costume that has no gameplay impact at all (or a lot of lesser cosmetics that have no gameplay impact at all). There are a WHOLE LOT of expensive costumes in this game. I'd take the money just for that reason, even WITH the money, if you try to grind enough cash for all the costumes before you reach the end of the game you will end up overleveled.

Also: The Dengeki costumes do have stats on them (most costumes don't). Once you get past about level 20 or so those stat bonuses are so minor as to be trivial, but you might want to avoid using them before that.

And yes, Peashy and Plutia are seriously OP at low level. Partly because they can go HDD, meaning you have three people in your party with HDD in fights where you were only expected to have one.

I went ahead and started the first game with all DLCs enabled, using 100,000 credits only for costumes that don't boost stats (as suggested by Bethezer and rankaze). After playing the game for about two hours, I still don't see costumes for purchases in the shop. If I buy any other items at the shop, I keep the credits above 100,000.

Seeing all the DLC healing items in my inventory, I turned off "Histy's Trial Item Package" and "Histy's Beginner's Item Package" DLCs. Didn't see the extra healing items disappear from the inventory, so I exit and restarted the game. Now these two DLCs show up as Purchase Req. instead of having the OFF / ON options, and each time I load the game, a "Could not find the applied content, [name of DLC]" message appears twice, once for each missing DLC. Oh, and the extra DLC items still appear in my inventory ;-)

EDIT: Fixed the message issue by setting DLC002=1 and DLC003=1 in Neptune.ini configuration settings under [DLC]. There seems to be no other way to prevent those messages from appearing, unless you start a new game with the DLCs disabled first. So I started anew with the following disabled in Neptune.ini:

DLC002=0
DLC003=0
DLC004=0
DLC005=0

The first two are just the extra healing items, and the last two are the DENGEKI costume DLCs but don't appear on the in-game DLC menu (from GOG's DLC package).

Btw, do Peashy and Plutia add significant extra story or events, or they're just useful for battle?

They are just for battle. There are no cutscenes or anything the like with them, as they actaully aren't supossed to ever be in this games dimension.

That means I won't miss out on anything if they're not put in my party, like you suggested earlier. I think that answers all my questions. Thanks guys