We are using the VS Team System with TFS, sharepoint, and the works even though we are a small team. VSTS source code control is iron-clad, and sharepoint services are great for building repositories and very nice team/project/portal sites quickly. The problem I have with TS is the workflow. While the package ships with a couple of workflows and associated forms out of the box (Agile development model and Extreme development model I believe), you have to know how to work with XML extensively in order to modify the existing models or to create workflow models from scratch.
The workflow and forms provisions are very configurable/customizable, but there is no GUI that I'm aware of to make it intuitive. This is the principal reason that I'm still using OnTime. If MS ever slaps a nice GUI on the product, I'll probably make the switch. Not that I don't like the OnTime product line; on the contrary, it's a great system, but we are trying to integrate our environment as much as possible. I believe I inquired of Axosoft when VS2K5 first came out whether or not they intended to integrate with the TS, and the answer was 'no' at the time. So, bottom line, if you have the resources available to manage your workflow/forms configurations, or you can use one the out-of-the-box workflows, VSTS provides a great, integrated, enterprise scale package for just about any environment.
On the downside, I will fore-warn not to exclude cost in your consideration, because VSTS is a substantial investment. Total cost for 3 IDEs, and the TFS was about $17K, and there are several flavors of the IDE to choose from, each having its own set of 'extras' that may cause you to buy lateral upgrades if you want to employ them. For instance, we have 3 copies of the Developer Edition IDE. MS created a utility for synchronizing SQL databases and managing their source/version/etc and released a 180-day beta. We used it and found it to significantly increase efficiency for sync processes. However, when the final release of the utility came out, we found that MS had made it a part of the Database Professional Edition of the IDE, and now we are forced to drop another $2300 to get the lateral upgrade.
Also on the downside, TFS setup and system and security configuration is not very intuitive, and is a bit difficult to master. Doumentation was sparse at the time we purchsed the system as well. If you have a faily open network policy, that makes it easier, but we were in the middle of a 'strap down,' which cause a few headaches in itself.
Chris
First rule of leadership...everything is your fault.- Hopper