Not all Wills must be witnessed. If the signature and material provisions are handwritten by the Testator, then it may qualify as a holographic Will. See California Probate Code Section 6111(a). Holographic Wills are generally done without the consultation of a lawyer and as a result contain often contain ambiguities or incomplete instructions as to how the Testator's assets are to be distributed. 

Commercially Printed Will?

California Probate Code Section 6111(c) states: "Any statement of testamentary intent contained in a holographic will may be set forth either in the testator’s own handwriting or as part of a commercially printed form will." Therefore, the use of commercially printed forms is permissible.

Invalidity?

If the holographic Will is not dated, there are some situations in which it may be found partially invalid. California Probate Code Section 6111(b) states:

b) If a holographic will does not contain a statement as to the date of its execution and:

(1) If the omission results in doubt as to whether its provisions or the inconsistent provisions of another will are controlling, the holographic will is invalid to the extent of the inconsistency unless the time of its execution is established to be after the date of execution of the other will.

(2) If it is established that the testator lacked testamentary capacity at any time during which the will might have been executed, the will is invalid unless it is established that it was executed at a time when the testator had testamentary capacity.

Holographic Wills can be helpful if drafted clearly enough. However, most laypeople who aren't familiar with the estate planning process are likely better off using the California Statutory Will form as an alternative to hiring a qualified estate planning lawyer.