It does change the graphics and its not as straight forward as TIR, you need to wear the Headset and be in the mindset and prepared for VR. But when you try it, you love it. Me, I only miss my TIR, which I sold to buy my VR, simply because now my Falcon BMS 4.34 became unplayable without it and in its current state, its light years ahead of DCS' F-16 in every aspect. In DCS, the only reason why I would use TIR instead of VR is to train BVR and Strikes. To actually play it, I always go VR for sure, it's amazing.
Also, TIR5 imo is the one really overpriced of the two options. £169 for the pro version, c'mon? It's better than the cheaper (£35) options for sure, but the small gain in performance cost a whole lot of money when its still just a little webcam with its ir filter removed, a trackclip and the better software.