Very well polished game
I'm surprised, I thought this game would have more positive reviews. It's got creative enemies and is relatively well polished except for the upgrade system.
PROTIP: If you're out of the planet for more than half a second when you're jumping out to attack non-air units, you're playing totally wrong. And probably dying too. Position your worm so that you jump out sideways to the planet's ground, so that you'll land back into safety after a very brief moment.
The controls definitely take some getting used to but it's not because the controls are bad, it's because it takes time to get used to the worm's limited ability to change directions quickly. Overall though they are very smooth and without the worm's bad turning the game would be far too easy and mundane. Well, except for all those people who don't seem to know how to attack without getting half of their health shot out in one jump.
That said, the upgrade system in this game is fairly useless. Health is virtually the only worthy upgrade, with attack helping a minor amount and speed only helping on the last boss. In fact I'm willing to bet if I only got the health upgrades and the rest didn't exist, the game would have been just as difficult without them. The health power-up was slightly useful though.
If an upgrade system exists in the game it should give a feeling of progression. Except for the health upgrades, the worm didn't feel like it was getting ANY stronger. The power-up level upgrades are too unreliable because the power-ups that appeared during levels are selected at random. There should be more customizability for useful stats on the worm instead, such as upgrading the worm's turning ability slightly or giving it a better chance/range of eating soldiers instead of knocking them aside.
That aside though, the game is very nice. Good music, very pleasing and cute graphics, relatively fast-paced action, moderate difficulty, and best of all relatively creative and fun enemies to fight. The fact that I have to change my target priorities in the middle of a level frequently is a good thing (Such as deciding whether to take out Lirium farmers or to attempt to pick out a few enemies on a less crowded side so I don't lose as much health, or attacking any dangerous jet soldiers who didn't have friends around to protect them at the moment).
Make the upgrade system more fun and appealing to use, and then this game could be a 10.