The 1 KB Flash is the hard limit for firmware; if your application already fits in 512 bytes, this part leaves headroom; if you're pushing 2 KB, look at the MSP430G2153 or G2231 in the same footprint.
Connectivity runs through I²C, SPI, and the Universal Serial Interface (USI), a flexible serial module that can be configured as either UART or SPI in software.
20-TSSOP package and supply range
Housed in a 20-pin TSSOP (4.40 mm width), the package is compact enough for space-constrained boards but still hand-solderable with a fine tip and steady hands — the 0.65 mm pitch is manageable for rework.