Is Spore as effective as on, when off

The main problem is the loss of any companions in creature phase, which can take time to regain; especially if you're taking other species with you.

No.

The Creature Creator was released as a quasi-demo shortly before the actual game. Even though it is something you have to pay for, it was released with the intention of users buying it to play with while they waited for the final game - with most stores offering rebates on the purchase price of this "demo". While it contains many of the options for body parts found in the full retail version, it lacks many others.

For example:

• Various body parts acquired through play will not be available.
• Earlier/Later stage creature customizations will not be available.
• Buildings/Vehicles will also not be available.

Additionally, the added parts that can be found in the "Creepy and Cute" expansion pack are not compatible with the Creature Creator.

I would strongly suggest buying the full version, as it's very often on sale, over the Creature Creator.