Travel Document Systems is a company that handles expedited passports and visas. The basic theory is that you send them a passport, and they hand-deliver it to the embassy and pick it up for you, and that way, if anything goes wrong, you've got someone dealing with it. In addition, you often get your visa faster, since many embassies process locally delivered ones faster than mail-ins.
This makes a lot of sense if the company you are dealing with is competent. This makes no sense if, as in the case of TDS, they are not. With an incompetent visa expediter, like TDS, you just add another agency into the mix who can cause problems, expenses, and delays.
I used their services twice. The first time, everything went smoothly. The second time, I had asked them to send me a duplicate invoice from the first time I used them, which they promised they would. Not only did they fail to do that, but when the passport arrived, they sat on it for three days, and did nothing with it. Eventually, I called them to check on status, and I found out that they still had not began processing it. The passport did not have enough blank space (it had blank pages in back that are reserved for ammendments and modifications, but I had gotten visas on those pages before; in addition, it has one nearly blank page with only one barely-visable stamp that was faded enough I did not notice it when sending it out).
They lied that they called me three times and left voicemail once. The problem is that I use a VoIP phone service, which keeps logs of all incoming calls and voicemails -- I had no voicemails from them, and I had no calls from TDS' phone number -- just one call from an unrecognized, unlisted phone number (I didn't think it belonged to TDS). They also had my e-mail address, but did not try e-mailing me. I don't know why they did not contact me -- maybe they wanted me to pay the higher expedite fees, but more likely, they were just disorganized and incompetent.
At this point, we were low enough on time that I had to pay large amounts of money to expedite everything, and even then, we were within the error margin for me getting the visa on time (processing time was 1-2 days, and if it took 1 day, we were fine, and if it took 2, we were not). Fortunately, it took one day, and I got the visa just in time to board the plane.
Sadly, in the end, the visa they sent me was defective -- the date on it was wrong (it was postdated by three months -- the field just said "date," which I assumed was date of expiration, but it was supposed to be date of issue). This was a problem on the end of the embassy, but again, TDS is in the business of catching and fixing that exact type of problem. When I flew into Nigeria, I was detained by customs, and eventually let into the country without a passport. I had to spend several days of my trip and a bit over $100 dealing of my money, and a decent chunk of my host's money (my host paid for car, driver, and sent an employee with me to Lagos when I was resolving this) trying to get my passport back and a correct visa issued.
From Nigeria, I flew straight to China, where I spent 3 months. After I returned to the States, over the coming months, I called, e-mailed, and mailed multiple times to try to get duplicate invoices. They did not respond to mail or e-mail, and over the phone, they first promised to send it, but never did. Later, told me it was too late, and that the information was no longer in their system (talking to them, they referenced my e-mail, so I found out that they read my e-mail, but simply did not bother to respond). This meant they keep information for less than a year -- much less than the IRS-recommended minimum of 3 years for all taxpayers (in some circumstances, the IRS requires you to keep records for 6-7 years).
Given the level of disorganization and incompetence, I would strongly suggest avoiding TDS. Use one of the many competitors. I've used Passports Plus once without issue. After the TDS incident, the MIT travel agent recommended VP2Go, and the transaction also went very smoothly (indeed, the details seemed more polished than either TDS or Passports Plus). The travel agent also recommended A Briggs, which is nice because it has a Boston office, but which I have not used. Of course, it is difficult to tell if the company is competent until issues come up -- most companies work fine when things are going smoothly -- with a visa expediter, the key question is how well they handle problems (since that's what you're paying them to do).