NEW YORK ( TheStreet) -- Research In Motion ( RIMM) unveiled its new PlayBook tablet Thursday at an odd, splashy party in New York City, where the company's co-CEOs mingled and chatted with the crowd but didn't take the stage or make any formal announcements.

The execs' low-profile could be due to an incident earlier this week, when Mike Lazaridis stormed out of an interview with a BBC reporter after he was asked about the security of its BlackBerry devices in certain Middle Eastern countries.

Instead, the spotlight revolved around the 7-inch PlayBook, which starts selling Tuesday for $499 at retailers like Best Buy ( BBY), Staples ( SPLS) and Office Depot ( ODP). The tablet has been widely praised for its ability to multitask and handle Adobe ( ADBE) Flash Web sites.

Most critics, however, have panned the device for not providing access to users' e-mail service, calendars and address book unless synced to a BlackBerry.

Reviewers also criticized the lack of apps available for the PlayBook. There were about 3,000 at launch, compared to the more than 65,000 designed specifically for Apple's ( AAPL - Get Report) iPad.

As company executives mentioned on their recent quarterly conference call, RIM hopes to close this gap by allowing Google ( GOOG - Get Report) Android-based apps to run on the PlayBook sometime this summer.

But without more apps, analysts say the device feels rushed and unfinished. "The PlayBook's lack of native e-mail and thin application presence is a critical omission," Oppenheimer analyst Ittai Kidron wrote in a research note. "While updates will address these, we feel perception doesn't change easily and mind share could be hard to recover."

The PlayBook launch comes at a crucial time for RIM, which continues to shed market share in the lucrative U.S. smartphone sector. As of February, RIM holds 28.9% of the smartphone OS market -- second place to Google's Android, according to Comscore. That percentage is down from 33.5% the three months prior.

Analysts, on average, expect RIM to sell around 3 million PlayBooks this year. Sales of tablet devices in the U.S. this year are expected to double over 2010 to 24.1 million units, according to market research firm Forrester.

The PlayBook is up against some stiff competition. Read on for updates on its most well-known competitors.

Motorola Xoom

Launched: February 2011

When Motorola's ( MMI - Get Report) Xoom tablet was released earlier this year, it was heralded as one of the first big challengers to Apple's market-leading iPad.

The first device to run on Google's ( GOOG - Get Report) tablet-specific Honeycomb operating system, the Xoom boasts a 10-inch screen and two cameras. Later this year, it can be upgraded to support Verizon's ( VZ) 4G network.

Unfortunately, sales of the Xoom have not taken off as expected.

According to Deutsche Bank, Motorola has sold about 100,000 tablets so far since launching in February. Apple, by comparison, sold between 400,000 and 500,000 iPad 2s in the first weekend of its release, according to reports.

"Our checks indicated slowing sales of the Xoom tablet and we believed the Xoom will struggle to sell versus iPad 2 and new Honeycomb tablets going forward," wrote Canaccord Genuity analyst T. Michael Walkley, in a recent research note.

The device's high price may be partially to blame for meager sales -- the Xoom goes for $800, or $600 with a two-year contract from Verizon. Consumers, said Forrester analyst Sarah Rotman Epps in a recent blog post, expect tablets to be priced somewhat low, despite the high cost of their production.

Samsung Galaxy Tab

Launched: November 2010

While the Samsung Galaxy tab was believed to be another major threat to the iPad following its release in November, popularity of the Android-based device remains somewhat cloudy.

In December, Samsung said it had sold 1 million devices, before announcing sales of 2 million just a month later. The company later retracted these figures, stating they actually represented the number of Galaxy Tabs that had been shipped to wireless companies and retailers.

When asked about actual sales figures, a Samsung executive said they were "quite smooth," but declined to give specific numbers.

Earlier this month, both Verizon and Sprint ( S) dropped the price of the Galaxy Tab to $200 with a two-year agreement. Verizon's version of the device originally cost $600 contract free, while Sprint's cost $400 with a contract.

This week Samsung released a WiFi-only version of the device for $350.

The Tab runs on Samsung's 1-gigahertz Hummingbird processor and Android 2.2. The Tab has proved to be surprisingly capable in informal tests performed by TheStreet.

In terms of battery life, the Galaxy Tab lasted two days on a single charge.

Cisco's Cius

Expected Launch: April 2011

Set to launch this month, Cisco's ( CSCO - Get Report) Cius hasn't yet attracted much buzz. The Cius, Cisco's first foray into the tablet market, is a 7-inch Android-based device designed primarily for business users.

The Cius weighs 1.15 lbs, includes front and rear facing cameras and will run on Verizon's 4G network. It is supported by Cisco's Unified Communications Manager and runs collaboration products like Quad, WebEx and Presence.

It remains unclear how Cisco's recent decision to cut part of its consumer unit will impact the Cius' launch.

Apple's iPad

Despite the flood of electronics manufacturers scrambling to grab tablet market share, Apple's iPad remains king.

The second-generation iPad flew off the shelves following its March release, selling an estimated 400,000 to 500,000 units during its first weekend on the market. Widespread sellouts of the device were reported, and Apple's online store still lists a waiting period of two to three weeks to ship the tablet.

Apple has not yet disclosed any sales figures, but should list sales metrics of all its products next Wednesday after the bell, when it reports fiscal second-quarter earnings.

The iPad 2 is a slimmer, lighter and faster version of the iPad 1. It is thinner than the iPhone 4 and runs on a dual-core A5 processor that is up to two times as fast than the original iPad. The device also features both rear-facing and front-facing cameras for FaceTime, as well as a 10-hour battery life. It runs on Verizon's and AT&T's ( T) 3G networks.

The Cupertino, Calif.-based electronics maker has sold around 15 million iPads since the debut last April, and the product line generated more than $9.5 billion in 2010.

Analysts predict sales of the iPad 2 could top 30 million in 2011.

--Written by Olivia Oran in New York.

>To follow the writer on Twitter, go to http://twitter.com/ozoran.