A great concept hampered by significant design flaws.
First of all, the things they did right. Spectrobes makes excellent use of the DS's multiple input and output functionality, using the dual screens at all times very effectively. The excavation part of the game makes excellent use of the touch screen and dual screen, and even the microphone, and the Spectrobe awakening mini-game utilizes the microphone really well, though it can often be a frustrating experience trying to hold the right volume for 3 seconds. The battle system is also very fun, just poorly balanced.
Now for the problems. First of all, the main character Rallen fights with your Spectrobes in battle, and while this wouldn't normally be a problem, it is when you take into account that Rallen never gains any experience or levels and is entirely reliant on equipment to increase his stats. On top of that, the equipment he gets is still pretty much entirely ineffective on all enemies, so it's pointless to invest in any offensive items - especially when you consider that the blaster and sword both drain your stamina gauge when you use them, preventing you from using a Spectrobe attack in conjunction - its better to just use the glove and punch enemies whenever necessary. Equipment and recovery items are also frustratingly expensive, particularly in the early game, when you might have to fight 5 to 10 battles just to buy a single weak healing item, and dozens and dozens of battles to get any of the equipment.
The battle system is also poorly balanced. The defense stat doesn't seem to do very much in reducing the damage taken, and the result is that if you play the game using normal attacks and avoiding the overpowered CH attacks, it becomes quite difficult (which some people might prefer). However, if you use the CH attacks, the game is ridiculously easy and not even really a challenge, or fun for that matter. The method for finding fossils and minerals is quite tedious as well, and could have been done better. Rather than showing an extension of the bottom screen on the top screen, for instance, it might have been better to show an X-ray of the ground beneath you so that you can see if there are things to excavate around. Seeing where you can find the items while you're exploring is a lot better than stopping to hold the R button every few paces.
There's also a few oddities in the design that are questionable. One thing that stood out to me is the fact that there seems to be absolutely no friction in the battle floor. Rallen and his Spectrobes will slide for a half second before coming to a stop whenever you stop moving, and if you try to turn you may find yourself fishtailing a bit. It's a strange effect, but doesn't really hamper the gameplay at all, it just looks weird.
Despite its flaws, Spectrobes still manages to be fairly entertaining. The excavation system is surprisingly addictive and fun, and the battles are quite fun, so long as you don't play cheap and use nothing but CH attacks. With a little work on the problems, Disney could easily turn this into a great franchise, but they need to rethink some of their ideas and rebalance the game's design. Give Rallen the ability to level up and actually be useful in battle, make equipment and items cheaper, and maybe even set the Spectrobes up to use some AI reminiscent of Kingdom Hearts or Star Ocean rather than requiring player input, and give each Spectrobe and Rallen their own stamina gauge rather than a shared one. Improve the fossil-finding system and add a lot more Spectrobes to the list (it's pretty puny with only 20 or so species, even if they do have 3 forms each). Hopefully there will be a second game in the series, and they'll fix the problems with the first, because it definitely has potential to be great.