My opinion of Treasure Strike, if made into a graph, would take on something of a U shape. When I first read a description of the game and saw a couple of screenshots, I thought "great! A Power Stone 2 clone with character creation!", unfortunately, I then played the game and my first impressions were more along the lines of "oh, it's not really like PS2 at all, and the character creation's not that great." I stubbornly kept playing, however, and that's where the graph goes right back up, as I realised "it's not like PS2, but it's still a ton of fun, and the character creation actually opens up a short time into the game".
You'll probably want some clarification on all that, right? Well, Treasure Strike's a 3D battle action game, in which you take on the mantle of a member of a town's treasure hunting guild, and you go to various places and find treasure, which can be sold to buy new weapons. The matches are a little unorthodox, as they see you running around various locations seeking out keys to open treasure chests. Keys come in three colours, and most chests are one or two of those three colours (two-coloured chests need both matching keys to open, and there are wooden chests that don't need a key at all). Each chest contains a treasure, but only one chest contains the target treasure needed to win the match. Obviously, your opponents all want the same thing too, and you're all armed with any two from the combination of melee weapons, guns and mines. Taking damage makes you drop treasure and keys, and running out of health sends you back to your homebase (which is also used for storing treasure, and to actually win the match, you need to get ahold of the target treasure and bring it back here). Yeah, at first, I was a little disappointed that it wasn't an all-out brawl, and the attack animations are a little slow and clunky, but after a few stages, the action becomes crazier and more manic, and a lot more fun. And the face that it's a treasure hunt rather than a fight gives the game a fairly unique screwball comedy feel.
The character creation mode is eacily the deepest I've seen on the Dreamcast, with the exception of Fire Pro Wrestling D, though like I said earlier, at the start of the game, you don't get much to work with. Upon starting a new story mode, you can choose your skin colour, hair style and colour, height, and facial features, all of which are permanent except hairstyle. You can't change your outfit until after you've won the first battle, which is annoying, but once you get the option, you'll spend at least half an hour customising stuff (at least, that's how it went for me). There's a massive array of clothes, accessories and hairstyles available, and the best thing is that they're all free! There's no tedious grinding to get the cool outfit you want like there is in a lot of more modern games with dressing up modes, and, your outfit has no bearing on your in-battle ability! Both things I definitely approve of.
Normally, I'm dead set against the idea of buying new weapons and upgrades in action games, but there are always exceptions of course, and Treasure Strike is one of them. In this case, it's an exception because like I've already mentioned, combat isn't actually a big thing in the game, and the advantage granted by buying more powerful weapons is pretty minimal. Plus, you'll probably be able to afford the most expensive weapons in the shop after only a couple of matches.
Along with all the good things this game has mechanically, you'll be pleased to know the developers haven't neglected the aesthetics. Everything looks great in this game: the locations look like cool, fun places, reminiscent of particularly well-designed theme parks. The characters are all amazing, too, the townspeople are a bunch of kooky-looking eccentrics (though the beauty salon/fashion boutique is owned by a pair of old fashioned gay stereotypes), your opponents all look like characters from a cool 90s shonen manga, and you'd really have to deliberately try if you wanted to make a character that wasn't cool, cute, or cool and cute.
Though it's a game that was clearly designed around a (now long-dead) online multiplayer mode, Treasure Strike does still have a full and robust single player mode, and though I haven't had the opportunity to try it out, it also has a split-screen multiplayer mode. Both of those things that modern developers with budgets several orders of magnitude larger than a Japan=only third party Dreamcast game would have had seemingly can't manage. It's also a ton of fun to play, so I totally recommend you do so as soon as possible.