This information is specific to US players, but should be similar for other regions. The notable exception being that PS3 players in UK/EMEA will need a key/code to access the beta:
North American Ghosts: here's the scoop on how to access the closed beta that starts on April 19th.
SPLINTER CELL OWNERS: You will have automatic access to the beta from your Splinter Cell disc on the 19th - no keys needed. However, you'll be receiving an email from us starting on April 19th with three Xbox beta access keys that you can share with friends to build your squad!
XBOX GAMESTOP PREORDERS: You will receive your beta key plus three Xbox buddy keys for you to share with friends to build your squad. Keys will be emailed to you starting on the 19th.
PLAYSTATION PLUS MEMBERS: all PlayStation Plus members will have immediate access to the beta on April 19th.
PC GAMERS: While there are no plans for a PC beta as of now, our devs are working hard to build an amazing GR: Future Soldier experience for you on PC. We'll keep you posted if anything changes.
I've been in the beta for this for a few days now, and not ONCE have I been able to get into a match. It just sits at the loading screen where it shows you the controls. The game isn't frozen or anything, it just never finishes loading into the match. Oh well.
Strange, I was playing it last night for the first time... I played 3 games in total, and from selecting 'Join game' to playing, it was quicker than CoD.