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 lines 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 .csv-files, for instance.
As txt2mat can perform string replacements before the numeric conversion is done, 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, provide appropriate format strings (as for sscanf), or split up the import process for huge files if you encounter memory problems.
txt2mat should work on Matlab R2007a and newer versions.
Comments and suggestions welcome.