Texas Instruments has marked the MSP430F5658IZQWT as obsolete. No last-time-buy window is listed here, so the only channel is surplus or independent distribution. The base product number is MSP430F5658.
With 74 I/O lines, this MCU can handle a fair amount of parallel interfacing — driving an LCD data bus, reading a bank of switches, or controlling external memory. The 12-bit ADC offers 16 multiplexed channels, enough for multi-sensor acquisition; the two 12-bit DAC channels can generate analog control voltages or reference levels. USB support (device or host, depending on firmware) is a strong feature for this class of 16-bit MCU.
Internal oscillator saves a crystal for many applications, though USB timing typically requires an external crystal for clock accuracy.