Time for the umbrellas.
Pay no attention to the parade rainers, rangelia. I'm willing to bet they have no personal experience with the antenna themselves.
A lot of people have reported success with these and they are not all stupid, crazy liars as some would have you believe.
If you want to build one, have at it. And be sure to let us know how it goes.
Even the manufacturer does not even state gain figures for that TAK-tenna. All they say is that it presents 10-12 dB of directivity which does not mean 10-12 dB gain. Any antenna that small is going to perform worse than a regular dipole yet due to it's construction will still show directivity. The same thing applies to the ferrite loop-stick antenna used in AM radios. They show great directivity yet have negative gain figures down in the double digits.
Does the TAK -tenna work? Sure it does but so did my 4 foot helical antenna on 160m. It worked but very poorly. Are there better antennas? Most definitely YES but as always, a poor antenna is much better than no antenna at all.