At 1st I was cool with the new challenge system, now I'm just disappointed/alone

I'm with you on having to login every day.  It's like if something in your real life happens, even if it's positive and fun they punish you for missing a day.  The timer should be much more generous.  Or at least only go down 1 red dot at a time and not 5.

I am facing the same issue where I bought this game with a group of friends on launch and am the only person playing it anymore, but this was mainly because of the horrendous balancing issues that took 4 months for popcap to get around to fixing.  By the time they made mostly everything okay my friends had moved on to other games and aren't willing to come back.  And while popcap already got their money for the game I guarantee you of the 4 of us I am the only person that will be buying GW3.  I feel like after the scared a lot of players away they did nothing to entice those players to come back (other than having a balanced game that should have been balanced in the first place) and haven't really rewarded the players that stuck around, which honestly anyone that played though the launch Rose and the months of buggedd Electro brainz should have been given something.

But the good news is I stuck with the game and it's really turned out to be fantastic, I feel like once popcap works on the Turf Takeover map balance then this game will be truly amazing and my ideal 3rd person shooter.

Doesn't even take that long to get your multiplier back up honestly. Doing all of the plant and zombie quests gets you back up to 1.75 so just keep easy quests in your quest log if you know you aren't going to play for a few days then you can get back to x2 easily.

If you ask me your friends are just being lazy and letting something small drive them away from the game ;p that or they just don't like the game

It has nothing to do with being lazy. It's the psychology of the system. I am an adult with a family, as are all of my friends. We have jobs and a family to deal with. The 1st PvsZ:GW was easy for us to play together in the evenings after work and the kids were in bed. Now there are challenges to do, that's what saps the fun. Some of us wanted to do challenges as quickly as possible in the time we had, which are easier done solo. The people who didn't care about challenges and just wanted us to play together just got frustrated and gave up. When you only have but a couple of hours the challenges can take up all of your playtime and that leaves no time for some good group fun in turf take over. The way the challenges were handled this time around is my problem. I could go on about the imp mech, I love the imp character and the IDEA but I think the mech is out of place. There are many other things I could talk about but I just don't have the time or know how to say it without probably being crucified. The game is still fun but it sometimes feels like there has been too much done to upset the awesome balance of the original. In fact I wouldn't mind seeing an online gardens and graveyards mode with just the original characters.
The Unicorn Chomper is awesome and deadly. I just had to get that off my chest, I see too many people complaining that it sucks. You have to re-learn how to play as a chomper with teleport. Once I figured it out, I loved it.

Ya in gw2 they beg you too much to keep playing. The first game was sooooo much simpler and better thats why i went back to it months ago. Just 247 gardens and graveyards and killing plants no more bs no more character upgrades no turf takeover no impossibly hard characters to get no deluxe edition exclusives no huge maps no annoying abilitys (apart from the goop) no nothing 

Then don't log in everyday.  The multiplier is just a bonus for XP gain but you are going to level up one way or the other.  You may not level as fast as people who play everyday, but that is still natural as people who play everyday will naturally gain more XP.

There are people that play everyday with the minimum multiplier and don't do challenges at all, which btw you are not obligated to do.  The only use for stars is the infinity and decorating your backyard.  You aren't missing any by not having the max multiplier.  Play when you feel like it.  The challenge board will continue to refresh if you want to raise your multiplier, but if you're just some casual player who pops in every now and then, then you shouldn't care how much XP you gain. 

what are you talking about more xp = more powerful characters faster 

Stars are a fast way to level characters, I leveled quite a few using stars almost exclusively. Again, till I'm probably blue in the face, it's the psychology of the system. I just want to point out my frustration to the DEVELOPERS. Maybe it can make a difference in the future on how challenges are handled. Personal opinion, what some one could or should do mean nothing in the face of the facts. The system is driving my friends and others away. I just want something different that will encourage my friends to stick around. I love the game and want it continue to do well. A good discussion on other options and ways to make the game better for all are more constructive. I love PvZ:GW, I have the shirts, figures from Diamond toys, Jaks and the Gamestop Exclusive Z-mech. I also have the time invested in both games to prove it. Don't be offended by honest criticism, it doesn't help anyone in the end. I want people, especially my gaming friends, to love the game like I do. 

 I love the fact that the game can be played solo or split screen against AI. It's a great feature but also a big problem. The 1st game was online ONLY, this was great because there were always lots of people to play with or against. The challenges were, of course online only. It would be nice to see some persistent challenges for online only, like turf takeover. (Other modes too of course.) Something like personally capturing a point, there could be other players present in the point. I'm not talking about a solo capture. (You wouldn't get credit for a team capture, your character has to be physically in the point.) Have it set at a certain amount of points captured and get rewards for milestones, coins, exp, or stars if you need them. It would also encourage people to actually do the freakin' objectives! It drives me crazy to see two attackers at a point with one defender. One attacker is in the point and one is standing outside of it just shooting. Jump in the point number two, it will advance the capture meter! 2 is greater than 1!