Short answer: For 2D, Yes it works and is usable on VATSIM, but don't expect consistent behavior. For VR headsets, some dials are unusable, rendering the plane unflyable unless you're handflying the whole way.
Long answer: It works under specific conditions (specific types of approaches, specific types of flightplans, specific autopilot modes, etc.). Outside of those, the behavior can be unpredictable. It depends on your comfort level with unknowns (including system nuances that are not representative of the real thing and cause more workload). The control logic for the dials on the FCP and the Baro set knobs are also incredibly inefficient to use, and not usable in VR at all with a mouse. Overall, the biggest gripes are:
FMS logic is unpredictable under certain situations
Vertical guidance (VNAV/Snowflake) is misleading or erroneous under anything more than the simplest VNAV calculations
Autoflight logic and control laws need a lot of reworking: premature turns, snaking, sudden trim jumps on AP reconnects, vertical mode during approaches are unpredictable and cause a lot of workload.
FADEC responsiveness is slow and too loose, causing N1 overshoots (inconsequential, but grating).
Then there's the "state of the art" issue: when the CRJ came out it was at its peak in terms of quality and features, which set it apart from anything from the FSX days. However, lots of devs have surpassed that benchmark since then with features that are above and beyond (see PMDG, Inibuilds, JustFlight, Carenado, Fenix-even-though-it-works-in-its-own-external-environment), which makes the CRJ in its current form really barebones (you get W&B control and some EFB options, but that's it). The CRJ is really overdue for a makeover that would bring it back in line with the rest of the products on the market.
Overall, however, it's useable on VATSIM if you're willing to accept some oddities here and there, and that there's a higher workload associated with dealing with those oddities that you don't see on the real aircraft.