I've used Construct 2 a bit, but haven't yet tried the new multi-player functionality which was actually only added in one of the recent beta releases; given their release history however there should be a stable release soon, which will include proper detailed documentation of this functionality.
If you haven't already done so, you might also ask in the Scirra forums. The community is passionate, friendly, and helpful, although they can sometimes be a little biased in favour of Construct 2 if you're trying to compare it to alternative options. You should also definitely download and try the free version before making a decision to purchase.
Updates to the software are very frequent, with a new beta version released every couple of weeks, and a new stable version after every 3-5 beta versions. New features are added constantly, and improvements are regularly made to existing features. Performance has improved drastically over the last year.
If you're targeting the web browser it's an absolutely fantastic option.
However, if you're targeting other platforms, do your research before purchasing; deployment, capabilities and performance are improving all the time, but, exporters for other platforms rely on third-party wrappers; sometimes these can involve a bit of work, and occasionally some minor features are not available on all platforms (this is noted in the documentation when it is the case). Simple games can run well on mobile, but more complex games can be difficult or impossible to optimise for acceptable performance. Exporting as a desktop application can also be tricky, with potential performance issues when running full-screen.
Because it provides a large, capable engine, there's also a certain amount of bloat; absolutely worth it if you're making good use of the features, but perhaps too much overhead for very simple games -- exporting a simple Pong game as a Windows application gives you a file-size of 20mb+ for example.
As expected, additional costs may be incurred for certain target platforms, although this is not Construct specific and applies to alternatives as well.
All round, I think it's an excellent piece of software, and potentially a great option, and I would definitely recommend it -- just be sure to do some basic research and ensure your expectations are appropriate to the capabilities of the software.
Hope that helps!