As txt2mat basically is a wrapper for sscanf, it quickly converts ascii files containing m-by-n numeric data, allowing for header lines. When encountering rows with different numbers of data elements, it will work line-by-line and thus slow down somewhat.
You may let txtmat carry out an automatic data layout analysis on comparatively 'simple' text files (header lines + decimal number data with common delimiters). By this analysis it is able to directly import most numeric .csv-files, for instance.
As txt2mat can perform string and regular expression replacements before the numeric conversion, it can cope with many irregularities within the data. By that it is also capable of detecting and handling commas as decimal characters (common german notation).
You can filter lines by keywords, skip lines by line number, provide appropriate format strings (as for sscanf), or split up the import process for huge files if you encounter memory problems.
You may also use the above to simply read the manipulated text into a string or to put each line into a separate cell without the numeric conversion.
txt2mat should work on Matlab R2007a and newer versions.
Comments and suggestions welcome.