Generally speaking, I think it’s awesome. Sigils are a form of art, after all. If someone has a strong enough connection to a piece of art that they want it permanently etched into their skin, that’s powerful stuff.
This is even more true for a sigil you’ve created. These are highly personal and meaningful creative works. If a piece of art is that important to you, I see no good reason it shouldn’t become a tattoo.
As far as the occult implications of sigil tattoos go, that’s a matter of personal philosophy and practice. There is no universally accepted take on sigil magick, just a variety of opinions and heated debate. Some people feel that sigils need to dismissed, forgotten and destroyed to have power, for instance. That stands in direct opposition to another tradition, originating well into prehistory, that occult symbols (runes, for instance) should be etched permanently in order to stand the test of time.
The important thing to remember in this debate, at least as it relates to things like tattoos, is that there’s more than one way to use a sigil. There’s the activation ritual outlined on this site, for instance, but there are also many, many other occult traditions that use sigils in other, equally meaningful ways. The thing to keep in mind is the intent. And if someone chooses to “activate” a sigil through the pain and expense of having it inked — or even if they just like it, and find the occult stuff a bunch of mumbo-jumbo — I find that no less valid or meaningful than a formal activation ritual.
As I’ve mentioned many times, the sigil itself isn’t anything magical. It’s a symbol, and the only meaning it has is the one you give it. It can certainly play a role in your personal motivation, meditative practice, spellcraft or prayer, but on it’s own it’s no more magical than if you’d written those same feelings and desires out as a haiku.
For that reason, I’ve never heard a particularly compelling reason why a sigil shouldn’t be used as a tattoo. Coming from a chaos magick perspective, my take is that if you like a sigil enough to even think about getting it tattooed, there’s probably something worth exploring there.