One big drawback is once the novelty has worn off, they will be equivalent to regular poker chips that simply have a decorative bitcoin symbol on them, because that's what they are. What denominates a chip is what the house says it is, so the printed BTC will serve no functional purpose.
The purpose of a poker chip is not to store value as much as it is to make it easy to handle value temporarily in the context of a game. That is why most people don't play poker with physical cash— it's damned inconvenient even though most people show up to a poker game with physical cash in hand. Once the game is over and the chips are put away, they no longer are considered to store value. Thus, I no more worry about my poker chips being stolen, regardless of what's printed on them, than I worry about my Monopoly money being stolen— that is actually a great convenience when dealing with the sums of money that are exchanged in some poker games.
And, the
BTC serves the exact same purpose as a
$: to help players keep track of what's going on in the game. Unfortunately, poker chips, even ones with no currency symbol on them, don't go down into sub-unit fractions. I suppose you could imagine that every chip has a value that is is actually the reciprocal of what's printed on it, but that poses its own problems.
Personally, I'm looking forward to the day when issuing milli-bitcoin, and eventually micro-bitcoin -denominated poker chips makes sense!