Limitations

No reading. The packages generate QR codes and barcodes; they do not detect or decode them in photos or scans.
The symbologies listed only: standard QR codes, Micro QR codes, rMQR codes, Code 39, Code 93, Code 128, GS1-128, EAN-8, EAN-13, UPC-A, Codabar and ITF. Other two-dimensional codes (Data Matrix, PDF417, Aztec) and other linear barcodes (UPC-E, GS1 DataBar) are not supported.
GS1 syntax only. GS1-128 elements are checked against the syntax rules of element strings, not against the GS1 dictionary of application identifiers: the format of the data and its check digits are not verified.
Mixed modes in standard QR codes only. QRCode.Create splits a text into segments of different modes, except a text with non-ASCII characters other than kanji and kana; Micro QR codes and rMQR codes encode the whole text in one mode. There is no API to choose the segments yourself.
ECI in standard QR codes only, and opt-in. Without QRCodeOptions.EciAssignmentNumber, the byte mode holds UTF-8 without an ECI designator. Micro QR codes and rMQR codes never have one.
No structured append: data too large for one QR code is not split across several codes.
Logos in SVG only. The PNG renderer and the image renderer do not draw logos; draw them on the image yourself.
No text under the bars in the SVG and PNG renderers: the image renderer prints it, with a font.
QR codes only in the terminal: the console renderer does not draw linear barcodes.