There is a minor learning curve with the software, but once this is passed, the software is relatively user friendly. The interface is logically ordered and the user guide/help is useful for problem solving purposes.
The best thing about the software is the sheer number of options for conducting virtually any conceivable analysis of geospatial data or remote sensing imagery.
On Windows machine, it does not use the native interface for saving and opening files, which makes navigating and saving large numbers of files somewhat cumbersome.
Also, since ENVI is the most comparable software in terms of capabilities, I found many instances where ENVI was easier to use or had functionality not available in ERDAS Imagine. For example, I found that creating ground control points using ENVI's automated process was easier than ERDAS, which requires manual entry for creating ground control points and warping imagery.
Particularly, I found that ERDAS Imagine was unable to handle certain file types that I needed for my research, particularly HDF and JP2 file types. In fact, I found the software to be somewhat temperamental in general, and spent a good deal of time investigating numerous error messages due the software's fickle nature. Therefore, while I was more familiar with ERDAS Imagine, I often felt compelled to use ENVI for ease of use or due to lack of analogous capabilities in ERDAS.
I am a graduate student at a university working on remote sensing applications for agriculture. I specifically used ERDAS Imagine to process imagery from Landsat 8 and Sentinel-2 satellites to examine changes in agricultural land use. The software was necessary for conducting much of my analysis of remotely sensed imagery and was particularly useful when conducting pre-processing for imagery.
Use of ERDAS Imagine software was critical for moving forward with my academic research and helped answer my primary research questions regarding the capacity of remote sensing to monitor and analyze agricultural land use.