I did not have a pleasurable experience with The MX Group, nor did my colleague who interviewed there in 2013.
They start off by having you take a skills assessment (WonderLic). Interesting test.
Interviews were absent of structure or flow, so there is very little time to ask questions of the interviewers. Most interviewers have little experience interviewing so that could explain the lack of structure.
Questions were more oriented to single word answers, rather than to spur creative dialog. While a few of the employees appeared to be knowledgeable in their domain (specifically the VP) there appears to be a lack of organizational exposure in alternative strategies for customer management and solution delivery. What may be interesting for some is that they are a pure custom development shop rather than a firm who has entered into strategic partnerships with other technology players.
Overall, I felt there was an overall pompous and dismissive attitude towards outsiders. A "country club" feel is prevalent, which for me was not something I desired. Probing on the customer base, role challenges, and overall Firm nature were often evaded or if addressed were answered with generic responses.
As for the positives, they appear to be using newer technologies for their customers. Additionally the location is great for those that live in the suburbs.