If you're interested in a steam deck but haven't reserved one yet, you might want to make a reservation soon. The Steam Deck page has been updated to show that reservations won't be able to be made until after Q3 2022, which means you shouldn't expect to get one.
If you're interested in a steam deck, you should put down the $5 required to make a reservation and secure your spot in line. Sean Hollister states in his review that the Steam Deck is an early access game console, but there was more to it than that. If you don't follow through with your order, the deposit will be returned.
There’s good news for the “after Q2 2022” crew
It seems demand is high enough that Valve is pushing the order timelines further into the year. There is some good news for those who had a reservation after Q2 2022, as Valve is starting to show that some should be able to make orders in Q3. You can check the Steam Deck page to see if there is an update on your order, my own reservation is in the Q3 group.
On February 25th, Valve took the first batches of steam deck orders, and on Monday it sent a second batches of emails. When you get your email from the company, you have 72 hours to make your purchase. Valve said in February that those with a Q1 order window would get an email by the end of March and that they would start going through the Q2 queue in April.
By the end of 2022, Valve plans to expand the availability of Steam Deck in more countries, including Japan. It's not clear which countries will be able to order the device.