With Visual Studio 2015 out to the public in several editions, Visual Studio 2015 Community stands out as the freebie in the batch. Not free as in open source -- Microsoft isn't quite that progressive -- but free as in beer, and intended (in Microsoft's words) "for creating modern applications for Windows, Android, and iOS, as well as Web applications and cloud services."
Unlike the for-pay versions of Visual Studio, Community is devised for and offered to non-enterprise and open source developers. How much will it appeal to those already on a free (or open source) IDE, especially when dealing with software stacks that aren't Microsoft's? The short answer: Pretty appealing, although it comes at the cost of dealing with some Microsoft-isms.
First among those catches is the licensing, which comes with some strings attached for corporate users. Individual users have no restrictions and can develop commercial apps freely, but organizations and enterprises are limited to use "in a classroom learning environment, for academic research, or for contributing to open source projects."
Next, consider the sheer size of Visual Studio Community compared to other IDEs. Those used to the single-folder installation of, say, Eclipse will faint when they see the sprawl of this program. A basic setup with the options selected by default, the Web developer tools alone, starts at 6GB and goes up from there. (My copy of Eclipse Luna, equipped for Python, Java, and Golang work, is only around 500MB on-disk.) Sprawling or not, a cold launch of Community on my system (a 16GB, 3.5GHz Intel Core i7) takes about the same time to kick off as Eclipse itself, around 5 seconds.
A gamut of third-party development add-ons for open source stacks are available through the Visual Studio Gallery. Unfortunately, not all of them have been updated for Visual Studio 2015. PHP Tools for Visual Studio, for instance, has been updated, but the one add-on for Golang support (not provided by Google) isn't.
Those already familiar with an existing incarnation of Visual Studio won't have to do much, if any, retooling. Community sports the same multipaneled interface and toolbars as its pro-level cousins, with add-ons managed in the same way.
The tools available for each particular language are delivered by the installed extension for that language and thus vary. That said, the bundled Python support compares favorably to solutions I've seen elsewhere. Syntax highlighting, an integrated debugger with stack-trace functionality, dependent projects, a class-based project view, performance profiling, and awareness of Python-specific things like virtual environments are all here. IntelliSense code completion is supported for those that want it (I did), although it can always be toggled off.
If you're looking to collaborate with others, don't expect to find any of Microsoft's Team Foundation Server tools in Visual Studio Community. Do expect, however, to find GitHub integration and support for Git (although the version installed by default is Git 1.95). GitHub connectivity shows up in the Team Explorer pane, same as it would for Visual Studio Online. I would have liked to see better integration for GitHub-tracked issues; right now, support consists only of a link back to the relevant GitHub-hosted project page.
Finally, what's missing compared to the for-pay editions of Visual Studio? Aside from cloud-hosted services like Visual Studio Online, other omissions include lab-management tools for setting up and tearing down test environments. CodeLens, IntelliTrace, and the other cloud-integrated debugging functions Microsoft has highlighted with Visual Studio are also absent. That said, most folks coming in without much of an existing investment in Microsoft likely won't mind, as they're apt to stick with their existing code-hosting and collaboration tools.
[Edited to clarify that Visual Studio Online, not Team Foundation Server, is one of the omitted features.]