This is my 1st electric toothbrush. I ordered it over the oral b smart 1500 because it's cheaper and I found more people who swear by it than oral b. Later on, I read comments where people who have this 4100 for 10+ years say that the newer 2021 version has only half the power of the old version. Someone on reddit showed images of the inside of the new and old versions and the new version has a small plastic toy-like motor, while the old version has a big copper-wrapped motor and an old version user said "now I understand why the new version is lighter and less powerful".I was disappointed on the new version and tried to cancel the order but I couldn't. Once it came, I decided to try it and to my surprise, it brushes my teeth way better than my manual soft-bristled and hard-bristled toothbrushes(I use both manual brushes daily compared to my daily usage of the electric toothbrush 4100 C2 head of medium bristles. If you have gum sensitive issue, buy the S sensitive or G2 optimal brush head. If you want hard-bristled, buy W diamondclean brush head).I don't know how good the old version was but this newer version definitely brushes better than any manual toothbrush unfortunately it doesn't not come with a travel case.Update 5/16/2024: I bought the Oral B smart 1500 because it was on sale and I wanted to see how better it is compared to the sonicare. The oral B package looks nicer and bigger than the Sonicare but upon opening the smart 1500 package, I saw hair all over the toothbrush. I did read many customers saying on reddit that their Oral b toothbrush were repackaged, but I can't believe I'm a victim of this nastiness. It also took 2 weeks to reach me from Hawaii and since it says "made in China", I think the seller is located in China.I'll return this and I'll advise you to buy the Sonicare instead of the oral b if you don't want to be cheated receiving a used-repackaged toothbrush.Update 05/22/2024: On 05/17/24, I bought the Oral b smart clean 360 which has exact power as the smart 1500 that I returned but the smart 360 has 5 modes and a button to change the mode while the smart 1500 has 3 modes and no button to switch between the modes.The advantage of the oral b smart clean 360 is that the brush heads cost is cheaper than the Sonicare 4100 and I find it better at whitening my teeth than the Sonicare. That's all the advantages there.The things that I don't like with it are many, so I'm just going to name the most annoying ones:1) The brush heads are too big compared to the Sonicare(see picture):Putting Oral b brush heads in my mouth is like putting a golf ball in my mouth(my head and mouth are wider than the average US male).2) The brush heads have holes(see pictures) that trap saliva+toothpaste and creates more noise when the brush handle needle rotates in the presence of the liquid mixture, and moisture will be also trapped easily in the holes(most customers complain about Oral b brush heads design. Oral b corrected the needle issue with the IO version but the IO introduced a shallow hole which now traps moisture in the brush handle).When I'm using the Oral b with no choice but to have my mouth wide-open, it forces my mouth to produce more saliva which gets mixed with the toothpaste and enters the brush head and creates more noise.3) Rattling noise: The Oral b smart clean 360 isn't as noisy as people say. It's the quality of the noise the problem. It's a very unpleasant rattling noise as if you're hearing an old car engine with broken parts in it. That noise gets worse when liquid enters the brush head holes.4) The charger is not round like a perfect circle:You must put the Oral b brush handle in a specific position to charge it and if you place it wrong, it'll fall and might break.5) The Daily Clean mode is rough and combined with the big brush head the experience is bad, but the smart clean 360 has more mode which make it smoother and better than the smart 1500 but not as good as the Sonicare 4100.6)It has no auto-stop mode: You keep brushing without knowing how long you have been brushing your teeth.To summarize, the oral b non-IO brush heads are cheap but very badly designed for a pleasant toothbrushing. I won't recommend it if you're shorter than 6 foot tall or have a small mouth.