No sailboat is great at sailing into the wind but the TI is particularly bad at it. With its very basic single mainsail, small dagger-board, and plastic kayak-style hull, this is not surprising. The TI is a decent daysailer but certainly not the best example of an efficient and agile sailboat.
If you find yourself in a situation where you have to sail close hauled in order to reach your destination or back to the shore, you can easily have difficulties, especially since approaching a shore might also involve fighting adverse currents. Sometimes, even with aggressive tacking, it's simply not possible to reach your desired destination with the TI given certain wind, wave, and currents. This should not surprise an experienced sailor, but those attempting to sail with the TI without a lot of experience might be taken aback that they can't get to their destination using the sail alone.
In this situation the MirageDrive can be a blessing, however, even with two people pedaling, this might not provide the power necessary to overcome certain adverse conditions.
Most sailboats, including the TI, should consider the use of an auxiliary motor, especially for large lakes and offshore use.
Here is some information on sharks relating to kayaking that also applies to the TI.