It's certainly better than nothing and will likely deter all but the targeted industrial (or governmental) espionage attacks. Then again, i'd rather use the best solution, rather than a "good enough" one.
If you are really concerned about industrial/governmental attacks, you should definitely read the "Maintenance" section in the TPM standard. It specifies an optional backdoor which allows the manufacturer to extract your keys from the TPM. Of course it's not called a "backdoor", it's just a convenient way to retrieve the so-called "non-migratable" keys when your motherboard dies, but you can imagine other uses.
I'd rather use a "good enough" solution with no known weaknesses against my threat model, than one which gives a false sense of absolute security. The key should not be in the laptop, even in a TPM, period.