If you prepare to play in the haphazard style it was built in, you should have some fun.
The levels in the game are divided up into different worlds, each with their own theme. These themes include forest, desert, ice & snow, lava, and more. Each world is accessible in various areas of a castle, which acts like your world hub.
To open each wing in the castle, you have to collect a certain amount of different Golden Idols, then you must collect enough of different types of crystals to gain access to each world. To open the final set of levels, you have to collect all of the Rune Stones hidden throughout the game. What I'm saying is, there's lots of collecting to do. The biggest annoyance for me was how all of this collecting meant it was necessary to replay past levels to move forward.
On the flip side however, you do not have to necessarily complete all the levels in each world before you're able to move on to the next world. Or more importantly, you do not have to beat the boss in each world before moving on to the next. This in fact is almost encouraged, because often there will be an artifact in the next world that will help you beat the boss from the previous world. Of course, to beat the game, you will have to face each boss eventually.
On top of the crystals, the artifacts, and special boss-fighting items, there's still more to collect and unlock. There's also bonus levels to find, where if you can complete them you can unlock new characters to play as. Power-ups are also abundant in this title. These work in a classic power-up fashion. They only last a short time, but give you stronger weapons, turn you into a giant, give you better defensive, and more.
As you progress throughout the game, you won't only have to rely on power-ups to make you stronger. Your character also levels up, gaining more strength, armor, speed, max health, and magic ability.
In fact, between he power-ups, the many levels, the unlockables, the characters, the bosses, the only thing that lacks in variety in this title is the actual game-play. You'll find that even with all of this, what you're doing at the end, isn't all that much different than what you were doing at the beginning. You'll need to press the attack button a lot more as the bad guys are tougher and more numerous, but for the most part (with the exception of one of the Dream Realm levels) it's mostly the same levels, switch-puzzles, and types of enemies with a different coat of paint for each world. It was still fun for me, and everything else kept it interesting enough for me to want to play through it, but others may get stuck in the rut of repetition.
Another component to the game that kept things fun was the humour. I thought there were plenty of funny parts, although I'm sure if they were always intentional. For example, the voice-over guy was cheesy, but in a good way. It was the sound of a man that didn't have a deep voice, but was pretending to. That made it even sweeter when you eat some food, and it goes "Nyum nyum yum yum num." His attempts at positive reinforcement was quite entertaining as well. Throwing lines like "Never before have I seen such bravery" and "That was a valiant effort" after you mow down a large number of baddies feels very parental. It felt just short of "Look at you, big boy, killing all those evil demons by yourself." There's also a bonus level where you're collecting coins in what is supposed to be the office of Midway Games, with all of their programmers sitting in their cubicles.
Uncomplicated action mixed with a variety of extras, makes this game a good choice for those that just want to kill a lot of things. With multi-player action, it seems like a great party game, and you may want the company as the trip could feel long if traveled alone.